Editing Linux 101 hacks (section)

='''Chapter 12: System Monitoring and'''=


'''Performance'''


=='''Hack 89. Free command'''==


free command displays all the necessary information about system physical (RAM) and swap memory.


Syntax: free <nowiki>[options]</nowiki>


'''What is the total RAM on my system?'''


In the example below, the total physical memory on this system is 1GB. The values displayed below are in KB.



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>free
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| total
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| used
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| free
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| shared
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| buffers
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| cached
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Mem: 1034624
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 1006696
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 27928
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 174136
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 615892
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| -/+ buffers/cache:
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 216668
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">817956</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Swap:
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">2031608</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">2031608</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
'''What is the total memory on my system including RAM and Swap?'''


In the following command:


o option m displays the values in MB


# option t displays the “Total” line, which is sum of physical and swap memory values 

# option o is to hide the buffers/cache line from the above example. 

# 
## '''free –mto '''

112
{| style="border-spacing:0;"
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">'''Linux 101 Hacks'''</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">www.thegeekstuff.com</div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">total</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">used</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">free</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">shared</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">buffers</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">cached</div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Mem:
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1010</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">983</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">27</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">170</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">601</div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Swap:
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1983</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1983</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Total:
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">2994</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">983</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">2011</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}

=='''Hack 90. Top Command'''==


top command displays real time information about various performance metrics of the system such as CPU Load, Memory Usage, Processes list etc.


Syntax: top <nowiki>[options]</nowiki>


'''How to view my current system status including CPU usage?'''


Execute top without any option from the command line, which will display the output shown below. The top command output will keep displaying the real-time values, until you press “Control + c” or q to exit from the command output.


<nowiki># </nowiki>'''top'''


top - 13:10:13 up 171 days, 20:21, 3 users, load average: 0.01, 0.05, 0.00



{| style="border-spacing:0;"
| colspan="8"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Tasks: 194 total, 1 running, 193 sleeping,
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0 stopped,
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 zombie</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Cpu(s):
| colspan="9"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.6% us, 0.7% sy, 0.0% ni, 98.7% id, 0.0% wa,
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.0% hi, 0.0% si

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Mem:
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 1034624k total,
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 1007420k used,
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 27204k free, 174540k buffers

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Swap:
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 2031608k total,
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="5"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0k used, 2031608k free,
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 615904k cached

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| PID USER
| colspan="7"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| PR NI VIRT RES SHR S %CPU %MEM
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">TIME+ COMMAND</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 11912 apache
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">15</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 31828</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 13m
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 3916 S
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.2</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0:46.35</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| httpd

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 19299
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| oracle
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">19</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">279m</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 18m
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 17m S
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.2</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0:00.03</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| oracle

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 11398 jsmith
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">16</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">107m</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 28m
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 6404 S
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.4</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0:03.07</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| perl

|}



'''How to read the output of the top command shown above?'''


# Line 1 “top”, indicates that the system has been up and running for 171 days. 

# Line 2 “Tasks”, displays the total number of processes along with a breakdown of running, sleeping, stopped and zombie processes count. 

# Line 3 “Cpu(s)” displays the current CPU utilization of the system. In this example, CPU is 98.7% idle 

# Line 4 “Mem” and line 5 “Swap” provides the memory information. This is the same information from the free command. 

# The rest of the lines display all the active processes on the system, sorted default by CPU usage (%CPU column). i.e the most CPU intensive processes will be displayed on the top by default. 

There are several command line options and interactive options available for top commands. Let us review couple of essential options for top command.


'''How to identify the most memory intensive processes?'''


While the output of the top command displayed, press F, which will display the following message and show all fields available for sorting, press n (which is for sorting the processes by Memory) and press enter. This will display the processes in the top output sorted by memory usage.


Current Sort Field: K for window 1:Def


Select sort field via field letter, type any other key to return


'''How to add additional fields (for e.g. CPU Time) to the top output?'''


While the top command is running, press f, which will display the following message and show all fields available for display, press l, which will add the CPU Time to the display columns in the top output.


Current Fields: AEHIOQTWKNMbcdfgjplrsuvyzX for window 1:Def


Toggle fields via field letter, type any other key to return


'''How to get the full path name and parameters of the running processes?'''


While the top command is running, press c, which will display full pathname of running processes as shown below in the command column. i.e Instead of httpd, it displays /usr/local/apache2/bin/httpd.



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| PID USER
| colspan="5"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| PR NI VIRT RES SHR S %CPU %MEM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">TIME+ COMMAND</div>

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 11912 apache
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">15</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 31828</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 13m
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 3916 S
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.2 0:46.35</div>

|-
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /usr/local/apache2/bin/httpd
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
'''How to view the individual CPUs in the top command?'''


While the top command is running, press 1 (number one), which will display the performance data of the individual CPUs on that machine as shown below.


top - 13:10:13 up 171 days, 20:21, 3 users, load average: 0.01, 0.05, 0.00 Tasks: 194 total, 1 running, 193 sleeping, 0 stopped, 0 zombie


Cpu0 : 10.2% us, 2.6% sy, 0.0% ni, 86.8% id, 0.3% wa, 0.0% hi, 0.0% si Cpu1 : 9.6% us, 8.0% sy, 0.0% ni, 82.4% id, 0.0% wa, 0.0% hi, 0.0% si Cpu2 : 1.3% us, 1.3% sy, 0.0% ni, 95.0% id, 2.3% wa, 0.0% hi, 0.0% si Cpu3 : 0.0% us, 0.0% sy, 0.0% ni, 100.0% id, 0.0% wa, 0.0% hi, 0.0% si115
{| style="border-spacing:0;"
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| '''Linux 101 Hacks'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| www.thegeekstuff.com

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Mem:
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 1034624k total,
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 1007420k used,
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 27204k free,
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 174540k buffers

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Swap:
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 2031608k total,
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0k used,
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 2031608k free,
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 615904k cached

|}

=='''Hack 91. Ps Command'''==


ps command (process status) will display snapshot information of all active processes.


Syntax: ps <nowiki>[options]</nowiki>


'''How to display all the processes running in the system?'''


Use "ps aux", as shown below.



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''ps aux | more'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| USER
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">PID %CPU %MEM</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">VSZ</div>
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| RSS TTY STAT START TIME COMMAND

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">2044</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">588 ?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Ss
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Jun27

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0:00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki>init [5]</nowiki>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| apache
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">31186</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1.6</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">23736 17556 ?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| S
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Jul26

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0:40</div>
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">/usr/local/apache2/bin/httpd</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| apache
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">31187</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1.3</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">20640 14444 ?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| S
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Jul26

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0:37</div>
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">/usr/local/apache2/bin/httpd</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
You can also use "ps -ef | more", to get a similar output


'''Print the Process Tree'''


You can use either '''ps axuf''' or '''ps –ejH''' to display processes in a tree format. The tree structure will help to visualize the process and it’s parent process immediately. For clarity purpose, few columns have been cut-off in the output below.


<nowiki># </nowiki>'''ps axuf'''116
{| style="border-spacing:0;"
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| '''Linux 101 Hacks'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| www.thegeekstuff.com

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Oct14
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 /opt/VRTSralus/bin/beremote

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Oct14
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| \_ /opt/VRTSralus/bin/beremote

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Oct14
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| \_ /opt/VRTSralus/bin/beremote

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Oct14
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| \_ /opt/VRTSralus/bin/beremote

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Oct14
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:01
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| \_ /opt/VRTSralus/bin/beremote

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Oct 14
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| \_ /opt/VRTSralus/bin/beremote

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Dec03
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:01 /usr/local/sbin/sshd

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Dec22
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 1:08 /usr/local/sbin/sshd

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 23:35
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| \_ /usr/local/sbin/sshd

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 511
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 23:35
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| \_ -bash

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 511
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| \_ ps axuf

|}
Note: You can also use pstree command to display process in tree structure.


'''View Processes Owned by a Particular User'''


The following command displays all the process owned by Linux user-name: oracle.



{| style="border-spacing:0;"
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| $ '''ps U oracle'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| PID TTY
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>STAT</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| TIME COMMAND

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 5014
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>Ss</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:01 /oracle/bin/tnslsnr

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 7124 ?
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>Ss</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 ora_q002_med

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 8206
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>Ss</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 ora_cjq0_med

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 8852
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>Ss</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:01 ora_pmon_med

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 8854
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>Ss</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 ora_psp0_med

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 8911
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>Ss</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:02 oraclemed (LOCAL=NO)

|}
'''View Processes Owned by Current User'''


Following command displays all the process owned by the current user.



{| style="border-spacing:0;"
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| $ '''ps U $USER'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| PID TTY
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">STAT</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| TIME COMMAND

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 10329
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| ?
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">S</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 sshd: ramesh@pts/1,pts/2

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 10330
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| pts/1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">Ss</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 -bash

|}
117
{| style="border-spacing:0;"
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| '''Linux 101 Hacks'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| www.thegeekstuff.com

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">10354</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| pts/2
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Ss+
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 -bash

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">10530</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| pts/1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| R+
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 ps U ramesh

|}

=='''Hack 92. Df Command'''==


df command (disk free) displays the amount of total and free disk space available on the mounted filesystems.


Syntax: df <nowiki>[options] </nowiki><nowiki>[name]</nowiki>


'''How much GB of disk space is free on my system?'''


Use df -h as shown below. Option -h displays the values in human readable format (for example: K for Kb, M for Mb and G for Gb). In the sample output below, / filesystem has 17GB of disk space available and /home/user filesystem has 70GB available.



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''df –h'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Filesystem
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">Size</div>
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Used Avail Use% Mounted on

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /dev/sda1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">64G</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 44G
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 17G
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">73%</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /dev/sdb1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">137G</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 67G
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 70G
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">49%</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /home/user

|}
'''What type of filesystem do I have on my system?'''


Option -T will display the information about the filesystem Type. In this example / and /home/user filesystems are ext2. Option -a will display all the filesystems, including the 0 size special filesystem used by the system.


<nowiki># </nowiki>'''df -Tha'''


Filesystem Type Size Used Avail Use% Mounted on118
{| style="border-spacing:0;"
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| '''Linux 101 Hacks'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| www.thegeekstuff.com

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /dev/sda1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">ext2</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>64G</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">44G</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">17G</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">73%</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /dev/sdb1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">ext2</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>137G</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">67G</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">70G</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">49%</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /home/user

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| none
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">proc</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">-</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /proc

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| none
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">sysfs</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">-</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /sys

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| none
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">devpts</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">-</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /dev/pts

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| none
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">tmpfs</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">2.0G</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">2.0G</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0%</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /dev/shm

|}

=='''Hack 93. Kill Command'''==


kill command can be used to terminate a running process. Typically this command is used to kill processes that are hanging and not responding.


Syntax: kill <nowiki>[options] </nowiki><nowiki>[pids|commands]</nowiki>


'''How to kill a hanging process?'''


First, identify the process id of the particular process that you would like to kill using the ps command. Once you know the process id, pass it as a parameter to the kill command. The example below shows how to kill the hanging apache httpd process. Please note that typically you should use “apachectl stop” to stop apache.



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''ps aux | grep httpd'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| USER
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">PID %CPU %MEM</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">VSZ</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| RSS TTY STAT START TIME COMMAND

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| apache
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">31186</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1.6</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">23736 17556 ?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| S
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Jul26

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0:40</div>
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">/usr/local/apache2/bin/httpd</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| apache
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">31187</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1.3</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">20640 14444 ?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| S
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Jul26

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0:37</div>
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">/usr/local/apache2/bin/httpd</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''kill 31186 31187'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}


Please note that the above command tries to terminate the process graciously by sending a signal called SIGTERM. If the process does not get terminated, you can forcefully terminate the process by passing a signal called SIGKILL, using the option -9 as shown below. You should either be the owner of the process or a privileged user to kill a process.


<nowiki># </nowiki>'''kill -9 31186 31187'''


Another way to kill multiple processes easily is by adding the following two functions to the .bash_profile.


function psgrep ()


{


ps aux | grep "$1" | grep -v 'grep'


}


function psterm ()


{


<nowiki>[ ${#} -eq 0 ] && echo "usage: $FUNCNAME STRING" && return 0 local pid</nowiki>


pid=$(ps ax | grep "$1" | grep -v grep | awk '{ print $1 }') echo -e "terminating '$1' / process(es):\n$pid"


kill -SIGTERM $pid



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| }
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="8"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Now do the following, to identify and kill all httpd processes.
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''psgrep http'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| USER
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">PID %CPU %MEM</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| VSZ
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">RSS TTY</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">STAT START</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| TIME

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| COMMAND
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| apache
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">31186</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1.6</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">23736</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">17556</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| S

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Jul26
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0:40</div>
| colspan="5"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">/usr/local/apache2/bin/httpd</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| apache
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">31187</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1.3</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">20640</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">14444</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| S

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Jul26
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0:37</div>
| colspan="5"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">/usr/local/apache2/bin/httpd</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
<nowiki># </nowiki>'''psterm httpd'''


terminating 'httpd' / process(es): 31186


31187


=='''Hack 94. Du Command'''==


du command (disk usage) will print the file space usage for a particular directory and its subdirectories.


'''How much space is taken by my home directory and all its subdirectories?'''


In the following example, option -s stands for summary only. i.e it displays only the total size of /home/jsmith and not the individual sizes of all the subdirectories inside the /home/jsmith. Option -h displays the information in a human readable format. i.e K for KB, M for MB and G for GB. The ~ indicates the user home directory. This command is same as “du -sh /home/jsmith”


<nowiki># </nowiki>'''du -sh ~'''


320M/home/jsmith


To get the subdirectories under /home/jsmith listed, execute the above command without the s option.


=='''Hack 95. lsof commands.'''==


Lsof stands for ls open files, which will list all the open files in the system. The open files include network connection, devices and directories. The output of the lsof command will have the following columns:


o COMMAND process name.


o PID process ID


o USER Username

o FD file descriptor


o TYPE node type of the file


o DEVICE device number


o SIZE file size


o NODE node number


o NAME full path of the file name.


'''View all open files of the system'''


Execute the lsof command without any parameter as shown below.



{| style="border-spacing:0;"
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''lsof | more'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| COMMAND
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| PID
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| USER
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| FD
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| TYPE
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">DEVICE</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| SIZE
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| NODE

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| NAME
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| init
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| cwd
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| DIR
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">8,1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">4096</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 2 /
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| init
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| rtd
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| DIR
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">8,1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 4096
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">2 /</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| init
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| txt
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| REG
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">8,1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 32684
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 983101 /sbin/init

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| init
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| mem
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| REG
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">8,1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>106397</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 166798 /lib/ld-

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 2.3.4.so
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| init
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| mem
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| REG
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">8,1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>1454802</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 166799

|-
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /lib/tls/libc-2.3.4.so
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| init
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| mem
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| REG
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">8,1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>53736</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">163964</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /lib/libsepol.so.1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| init
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| mem
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| REG
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">8,1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>56328</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">166811</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /lib/libselinux.so.1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| init
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 10u
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| FIFO
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0,13</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 972 /dev/initctl

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| migration
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">2</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root cwd
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| DIR
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">8,1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">4096</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">2 /</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| skipped…
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
The lsof command by itself without may return lot of records as output, which may not be very meaningful except to give you a rough idea about how


many files are open in the system at any given point of view as shown below.


<nowiki># </nowiki>'''lsof | wc -l'''


3093


'''View open files by a specific user'''


Use lsof –u option to display all the files opened by a specific user.



{| style="border-spacing:0;"
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''lsof –u ramesh'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| vi
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">7190</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| ramesh
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| txt
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">REG</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">8,1</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">474608</div>

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 475196 /bin/vi
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| sshd
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">7163</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| ramesh
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 3u
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">IPv6</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">15088263</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
TCP dev-db:ssh->abc-12-12-12-12.socal.res.rr.com:2631 (ESTABLISHED)


A system administrator can use this command to get some idea on what users are executing on the system.


'''List Users of a particular file'''


If you like to view all the users who are using a particular file, use lsof as shown below. In this example, it displays all users who are currently using vi.



{| style="border-spacing:0;"
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>lsof /bin/vi
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| COMMAND
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">PID</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| USER
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">FD</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">TYPE DEVICE</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">SIZE</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">NODE</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| NAME

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| vi
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">7258</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">txt</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| REG
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">8,1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">474608</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">475196</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /bin/vi

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| vi
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">7300</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">ramesh txt</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| REG
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">8,1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">474608</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">475196</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /bin/vi

|}



=='''Hack 96. Sar Command'''==


Sar commands comes with the sysstat package. Make sure sysstat is installed. If you don’t have sar installed on your system, get it from [http://pagesperso-orange.fr/sebastien.godard/ ][http://pagesperso-orange.fr/sebastien.godard/ Sysstat project].


Sar is an excellent monitoring tool that displays performance data of pretty much every resource of the system including CPU, memory, IO, paging, networking, interrupts etc.,


Sar Collects, Reports (displays) and Saves the performance data. Let us look at all the three aspects separately


'''Sadc - System activity data collector'''


<nowiki>/usr/lib/sadc (System activity data collector) command collects the system data at a specified time interval. This uses the daily activity data file that is located under /va/log/sa/sa[dd], where dd is the current day.</nowiki>


'''Sa1 shell-script'''


/usr/lib/sa1 in-turn calls the /usr/lib/sadcs. sa1 is invoked from the crontab as shown below. Run this every 5 minutes or 15 minutes depending on your need. I prefer to schedule it for every 5 minutes in the cron tab as shown below.


<nowiki>*/5 </nowiki><nowiki>* </nowiki><nowiki>* </nowiki><nowiki>* </nowiki><nowiki>* </nowiki>root /usr/lib/sa/sa1 1 1


'''Sa2 shell-script'''


<nowiki>/usr/lib/sa2 is a shell script that will write a daily report in the /var/log/sa/sa[dd] file, where dd is the current day. Invoke the sa2 from the crontab once a day at midnight.</nowiki>


<nowiki># </nowiki>59 23 <nowiki>* </nowiki><nowiki>* </nowiki><nowiki>* </nowiki>root /usr/lib/sa/sa2 –A


'''Note: '''/etc/cron.d/sysstat files comes with the sysstat package that includes''' '''some default value for the sa1 and sa2, which you can change accordingly.


'''Display CPU Statistics using Sar Command'''



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''sar –u'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Linux 2.6.9-42.ELsmp (dev-db)
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">01/01/2009</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:00:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| CPU
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| %user
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">%nice</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">%system</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">%iowait</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| %idle

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:05:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| all
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 3.70
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.85</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 95.45

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:10:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| all
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 4.59
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1.19</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.06</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 94.16

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:15:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| all
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 3.90
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.95</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.04</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 95.11

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:20:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| all
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 4.06
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.01</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 94.93

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:25:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| all
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 3.89
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.87</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 95.23

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:30:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| all
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 3.89
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.87</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 95.23

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Skipped..
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Average: all
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 4.56
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.15</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 94.29

|}
'''Note: '''If you need a break down of the performance data for the individual''' '''CPU’s, execute the following command.


<nowiki># </nowiki>sar -u -P ALL


'''Display Disk IO Statistics using sar command'''



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''sar –d'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Linux 2.6.9-42.ELsmp (dev-db)
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">01/01/2009</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:00:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| DEV
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| tps
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">rd_sec/s</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| wr_sec/s

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:05:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| dev2-0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 1.65
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1.28</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 45.43

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:10:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| dev8-1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">4.08</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>8.11</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 21.81

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Skipped..
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Average:
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| dev2-0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 4.66
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>120.77</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 69.45

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Average:
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| dev8-1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1.89</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <center>3.17</center>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 8.02

|}
125
{| style="border-spacing:0;"
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| '''Linux 101 Hacks'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">www.thegeekstuff.com</div>

|-
| colspan="7"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| '''Display networking Statistics using sar command'''
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''sar -n DEV | more'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="5"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Linux 2.6.9-42.ELsmp (dev-db)
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">01/01/2009</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:00:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">IFACE</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">rxpck/s</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">txpck/s</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">rxbyt/s</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">txbyt/s</div>

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| rxcmp/s
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| txcmp/
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| s
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">rxmcst/s</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:05:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">lo</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.17</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.16</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">25.31</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">23.33</div>

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.00
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:10:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">eth0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">52.92</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">53.64</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">10169.74</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">12178.57</div>

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.00
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.00</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''sar -n SOCK |more'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="5"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Linux 2.6.9-42.ELsmp (dev-db)
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">01/01/2009</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:00:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">totsck</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">tcpsck</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">udpsck</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">rawsck</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">ip-frag</div>

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:05:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">50</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">13</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">3</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:10:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">50</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">13</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">4</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 12:15:01 AM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">53</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">13</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">5</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>

|}
=='''Hack 97. vmstat Command'''==


For a typical performance monitoring all you need is only vmstat command. This display memory, swap, IO, system and cpu performance information.


The following command executes vmstat every 1 second for 100 times.



{| style="border-spacing:0;"
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''vmstat 1 100'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| procs
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki>-----------</nowiki>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| memory----------
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| ---
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| swap--
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right"><nowiki>-----</nowiki></div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">io----</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">--system--</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right"><nowiki>----cpu----</nowiki></div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| r
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| b
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| swpd
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| free
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| buff cache
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| si
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| so
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">bi</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">bo</div>
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">in cs us sy id wa</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0 282120 134108 5797012
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 2
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 100</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0 282120 134108 5797012
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0 1007
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">359</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 0 100</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>

|}
126
{| style="border-spacing:0;"
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">'''Linux 101 Hacks'''</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">www.thegeekstuff.com</div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 282120 134108 5797012</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 1117</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">577</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 100</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 282120 134108 5797012</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 1007</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">366</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 100</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>

|}
'''Vmstat procs Section'''


o r field: Total number of runnable process o b field: Total number of blocked process


'''Memory section'''


o Swpd field: Used swap space o Free field: Available free RAM


o Buff field: RAM used for buffers


o Cache field: RAM used for filesystem cache


'''Swap Section'''


o Si field: Amount of memory swapped from disk per second o So field: Amount of memory swapped to disk per second


'''IO Section'''


o Bi field: Blocks received from disk o Bo field: Blocks sent to disk.


'''System Section'''


o In field: Number of interrupts per second.


o Cs field: Number of context switches per second.


'''CPU Section'''


o Us field: Time spend running user code. (non-kernel code)


o Sy field: Time spent running kernel code.


o Id field: Idle time.


o Wa field: Time spent waiting for the IO


=='''Hack 98. Netstat Command'''==


Netstat command displays the network related information such as network connections, routing tables, interface statistics. Following are few examples on how to use netstat command.


'''Display Active Internet Connections and domain sockets using netstat'''


<nowiki># </nowiki>'''netstat –an'''


Active Internet connections (servers and established)



{| style="border-spacing:0;"
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Proto Recv-Q Send-Q
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Local Address
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Foreign

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Address
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| State
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| tcp
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.0.0.0:5666
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.0.0.0:*

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| LISTEN
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| tcp
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.0.0.0:111
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.0.0.0:*

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| LISTEN
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| tcp
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.0.0.0:4086
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0.0.0.0:*

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| LISTEN
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| skipped..
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
Active UNIX domain sockets (servers and established)



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Proto
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| RefCnt Flags
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Type
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| State
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| I-Node Path

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| unix
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 2
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki>[ </nowiki>ACC ]
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| STREAM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| LISTENING
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 7894

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /tmp/.font-unix/fs7100
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| unix
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 2
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki>[ </nowiki>ACC ]
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| STREAM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| LISTENING
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 9662

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /tmp/.gdm_socket
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| unix
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 2
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki>[ </nowiki>ACC ]
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| STREAM
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| LISTENING
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 10897

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| @/tmp/fam-root-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}



'''Display Active Connections with Process ID and Program Name'''


This could be very helpful to identify which program has initiated a specific network connection.


<nowiki># </nowiki>'''netstat -tap'''


Active Internet connections (servers and established)



{| style="border-spacing:0;"
| colspan="5"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Proto Recv-Q Send-Q Local Address
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">Foreign</div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Address
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| State
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">PID/Program name</div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| tcp
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki>*:nrpe</nowiki>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right"><nowiki>*:*</nowiki></div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| LISTEN
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 16277/xinetd
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| tcp
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| localhost.localdomain:smtp
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right"><nowiki>*:*</nowiki></div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| LISTEN
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 7263/sendmail: acce
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| tcp
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">34</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| localhost.localdomain:54221
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| localhost.localdomain:4089
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| CLOSE_WAIT
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">29881/httpd</div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| tcp
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">3216</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| dev-db:ssh
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">cpe-76-</div>

|}
94-215-154.soca:4682 ESTABLISHED 11717/sshd: ramesh


'''Display Routing Table'''


<nowiki># </nowiki>'''netstat –-route'''



{| style="border-spacing:0;"
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Kernel IP routing table
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Destination
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Gateway
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">Genmask</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Flags
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">MSS</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| Window
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">irtt Iface</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 192.168.1.0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right"><nowiki>*</nowiki></div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">255.255.255.0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| U
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 0</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0 eth0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 162.244.0.0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki>*</nowiki>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">255.255.0.0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| U
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0 eth0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| default
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 192.168.1.1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0.0.0.0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| UG
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 0</div>
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0 eth0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| '''Display RAW network statistics'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
<nowiki># </nowiki>'''netstat --statistics --raw'''


Ip:


11080343 total packets received


# forwarded 

# with unknown protocol 

0 incoming packets discarded


11037744 incoming packets delivered


11199763 requests sent out Icmp:

577135 ICMP messages received


64 input ICMP message failed. ICMP input histogram:


destination unreachable: 537 timeout in transit: 65 source quenches: 2

echo requests: 576476 echo replies: 12 timestamp request: 3 address mask request: 3


581558 ICMP messages sent


0 ICMP messages failed ICMP output histogram:


destination unreachable: 5079 echo replies: 576476 timestamp replies: 3


'''Misc Netstat Commands'''


# '''<nowiki># netstat –-tcp –-numeric </nowiki>'''List of TCP connection to and from the''' '''machine. 

# '''<nowiki># netstat --tcp --listening –-programs </nowiki>'''Display TCP port that the''' '''server is listening on along with the program that is listening on that particular port. 

o '''<nowiki># netstat –rnC</nowiki>''' Display the routing cache


=='''Hack 99. Sysctl Command'''Linux kernel parameter can be changed on the fly using sysctl command.==





Sysctl helps to configure the Linux kernel parameters during runtime.



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''sysctl –a'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| dev.cdrom.autoclose <nowiki>= </nowiki>1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| fs.quota.writes <nowiki>= </nowiki>0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| kernel.ctrl-alt-del <nowiki>= </nowiki>0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| kernel.domainname <nowiki>= </nowiki>(none)
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| kernel.exec-shield <nowiki>= </nowiki>1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| net.core.somaxconn <nowiki>= </nowiki>128
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| net.ipv4.tcp_window_scaling <nowiki>= </nowiki>1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| net.ipv4.tcp_wmem <nowiki>= </nowiki>4096
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">16384</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">131072</div>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| net.ipv6.route.mtu_expires <nowiki>= </nowiki>600
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| sunrpc.udp_slot_table_entries <nowiki>= </nowiki>16
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| vm.block_dump <nowiki>= </nowiki>0
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
'''Modify Kernel parameter in /etc/sysctl.conf for permanent change'''


After modifying the kernel parameter in the /etc/sysctl.conf, execute sysctl – p to commit the changes. The changes will still be there after the reboot.


# vi /etc/sysctl.conf 

# '''sysctl –p '''

'''Modify kernel parameter temporarily'''


To temporarily modify a kernel parameter, execute the following command. Please note that after reboot these changes will be lost.


<nowiki># </nowiki>sysctl –w {variable-name=value}


=='''Hack 100. Nice Command'''==


Kernel decides how much processor time is required for a process based on the nice value. Possible nice value range is: -20 to 20. A process that has a nice value of -20 is very high priority. The process that has a nice value of 20 is very low priority.


Use ps axl to display the nice value of all running process as shown below.



{| style="border-spacing:0;"
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki># </nowiki>'''ps axl'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| F
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">UID</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">PID</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">PPID PRI</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| NI
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">VSZ</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| RSS WCHAN
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| STAT TTY

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| TIME COMMAND
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 4
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">16</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">2172</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">552</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| -
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| S
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:17 init <nowiki>[5]</nowiki>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">3</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">34</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">19</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| ksofti SN
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>

|-
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 3:18 <nowiki>[ksoftirqd/0]</nowiki>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 1
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">10</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">5 -10</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| worker <nowiki>S<</nowiki>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:01 <nowiki>[events/0]</nowiki>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 4
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">5145</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">1</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">25</div>
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 10 32124 18592 -
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| SNs
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>

|-
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:08 /usr/bin/python
| colspan="7"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">/usr/bin/rhn-applet-gui --sm-client-id</div>

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| default4
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 4
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">5147</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">5142</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">16</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">3528</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">604</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| -
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| S
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>

|-
| colspan="7"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 /sbin/pam_timestamp_check -d
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| root
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 1
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">503 17552</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">4180</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">16</div>
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 14208 3920</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| -
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| S
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">?</div>

|-
| colspan="8"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:01 /home/www/apache2/bin/httpd -f
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="7"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| /home/www/apache2/conf/httpd.conf
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| -k start
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
'''How to assign a low priority to a shell-script? (higher nice value)'''


In the example below, when I started the nice-test.sh script in the background, it took the nice value of 0.


$ ./nice-test.sh & <nowiki>[3] 13009</nowiki>


$ ps axl | grep nice-test


0 509 13009 12863 17 0 4652 972 wait S

pts/10:00 /bin/bash ./nice-test.sh


<nowiki>[</nowiki>'''Note''': 6<sup>th</sup> column with value 0 is the nice.]


Now, let us execute the same shell script with a different nice value as shown below.



{| style="border-spacing:0;"
| colspan="5"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| $ '''nice -10 ./nice-test.sh &'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki>[1]</nowiki>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 13016
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| $ ps axl | grep nice-test
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 509 13016 12863
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">30</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">10</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">4236</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 968 wait
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| SN

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| pts/1
| colspan="5"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 /bin/bash ./nice-test.sh
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
<nowiki>[</nowiki>'''Note''': 6<sup>th</sup> column with value 10 is the nice value for the shell-script.]


'''How to assign a high priority to a shell-script? (Lower nice value)'''


In the following example, let us assign a nice value of -10 (minus 10) to the nice-test.sh shellscript.


$ '''nice --10 ./nice-test.sh &'''


<nowiki>[1] </nowiki>13021


$ nice: cannot set priority: Permission denied


'''Note: '''Only root user can set a negative nice value. Login as root and try the''' '''same. Please note that there is a double dash before the 10 in the nice command below.


# '''nice --10 ./nice-test.sh & '''

<nowiki>[1] </nowiki>13060 


# ps axl | grep nice-test 


{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 4
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0 13060 13024</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">10 -10</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">5388</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 964 wait
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki>S<</nowiki>

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| pts/1
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 /bin/bash ./nice-test.sh
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}



<nowiki>[Note: 6</nowiki><sup>th</sup> column with value -10 is the nice value of the shell-script.]


=='''Hack 101. Renice Command'''==


Renice alters the scheduling priority of a running process.


'''How to decrease the priority of a running process? (Increase nice)'''


In the example below, an existing shell-script is running at nice value of 10. (6<sup>th</sup> column in the ps output)



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| $
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">ps axl | grep nice-test</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">509 13245 13216</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">30</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">10</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">5244</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 968 wait
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| SN

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| pts/1
| colspan="5"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 /bin/bash ./nice-test.sh
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
To increase the nice value (thus reducing the priority), execute the renice command as shown below.


$ '''renice 16 -p 13245'''


13245: old priority 10, new priority 16



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| $
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">ps axl | grep nice-test</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">509 13245 13216</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">36</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">16</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">5244</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 968 wait
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| SN

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| pts/1
| colspan="5"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 /bin/bash ./nice-test.sh
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
<nowiki>[</nowiki>'''Note''': Now, the 6<sup>th</sup> column of the nice-test.sh (PID 13245) shows the new nice value of 16.]


'''How to increase the priority of a running process? (Decrease nice)'''


In the example below, an existing shell-script is running at a nice value of 10.134
{| style="border-spacing:0;"
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| '''Linux 101 Hacks'''
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| www.thegeekstuff.com

|-
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| (6<sup>th</sup> column in the ps output)
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| colspan="4"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| $ ps axl | grep nice-test
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">509 13254 13216</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">30</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">10</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">4412</div>
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 968 wait
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| SN

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| pts/1
| colspan="6"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0:00 /bin/bash ./nice-test.sh
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
In increase the priority, give a lower nice value as shown below. However, only root can increase the priority of a running process, else you’ll get the following error message.


$ '''renice 5 -p 13254'''


renice: 13254: setpriority: Permission denied Login as root to increase the priority of a running process


$ su -


<nowiki># </nowiki>'''renice 5 -p 13254'''


13254: old priority 10, new priority 5



{| style="border-spacing:0;"
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <nowiki>#</nowiki>
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">ps axl | grep nice-test</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|-
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 0
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">509 13254 13216</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">25</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 5
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">4412</div>
| style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 968 wait
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| SN

|-
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| pts/1
| colspan="2"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| <div align="right">0:00 /bin/bash</div>
| colspan="3"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| ./nice-test.sh
| colspan="0"  style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| 

|}
<nowiki>[</nowiki>'''Note''': The 6<sup>th</sup> column now shows a lower nice value of 5 (increased priority)]


'''12 Amazing and Essential Linux Books'''


For further reading on Linux, I recommend the following books. The 12 Linux books mentioned here by no means are comprehensive or authoritative list. But, these 12 Books are few of my favorites that I enjoyed reading over the years and I strongly believe will enhance your technical abilities on Linux, if you have not read them yet.


# [http://www.amazon.com/gp/product/1565922255?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1565922255 ][http://www.amazon.com/gp/product/1565922255?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1565922255 Sed and Awk], by Dale Dougherty and Arnold Robbins'''. Sed and Awk''' '''have transformed the way I worked on Linux command line. This book is the only material you would ever need on Sed and Awk. Once you’ve mastered even the basics of Sed and Awk, you’ll be amazed with the amount of complex tasks you can perform very quickly and elegently. For my day-to-day quick reference of sed and awk examples, I use the Sed and Awk Pocket Reference, written by the same author. 

# [http://www.amazon.com/gp/product/059652983X?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=059652983X ][http://www.amazon.com/gp/product/059652983X?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=059652983X Learning the Vi and Vim Editors], by Arnold Robbins'''. I’m a''' '''command-line junkie. So, naturally I’m a huge fan of Vi and Vim editors. Several years back, when I wrote lot of C code on Linux, I used to carry the Vi editor pocket reference with me all the times. Even if you’ve been using Vi and Vim Editors for several years and have not read this book, please do yourself a favor and read this book. You’ll be amazed with the capabilities of Vim editor. 

# [http://www.amazon.com/gp/product/0596526784?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596526784 ][http://www.amazon.com/gp/product/0596526784?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596526784 Bash Cookbook], by Carl Albing, JP Vossen and Cameron Newham'''.''' '''Whether you are a sysadmin, DBA or a developer, you have to write shell script at some point. A wise sysadmin knows that once you’ve mastered the shell-scripting techniques, you can put your servers on auto-pilot mode by letting the shell-scripts do the grunt work. To get to the auto-pilot mode of sysadmin, you definitely need to master the examples provided in this cookbook. There are quiet few Bash shell books out there. But, this books tops them all by giving lot of detailed examples. 

# [http://www.amazon.com/gp/product/0596008953?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596008953 ][http://www.amazon.com/gp/product/0596008953?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596008953 SSH, The Secure Shell], by Daniel J. Barrett, Richard E. Silverman and Robert G. Byrnes'''. This is hands-down the best book on SSH. This''' '''book explains both theoretical and practical aspects of SSH. Using 




SSH as an end-user is fairly straight forward . But, configuring SSH as an administrator is complex and involves a detailed understanding of SSH. This is a must read for any system administrator. The examples in this book show exactly what needs to be done differently for the different flavors of SSH such as SSH1, SSH2 and OpenSSH.


# [http://www.amazon.com/gp/product/0596003439?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596003439 ][http://www.amazon.com/gp/product/0596003439?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596003439 Essential System Administration], by Æleen Frisch. '''This is an''' '''excellent book for those who like to become a Unix System Administrator. This book covers all the typical system administration tasks. This is a perfect companion when you are dealing with multiple flavors of Unix, as it has examples for AIX, FreeBSD, HP-UX, Linux, Solaris and Tru64. I’ve used the pocket version of this book — Essential System Administration Pocket Reference, when I was managing multiple flavors of Unix systems at the same time. 

# [http://www.amazon.com/gp/product/0596004613?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596004613 ][http://www.amazon.com/gp/product/0596004613?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596004613 Linux Server Hacks, Volume One], by Rob Flickenger'''. 100 awesome''' '''practical hacks packed in one book. Setup a Linux test bed and try out all these hacks. These hacks are neatly grouped into different sections — Server Basics, Revision Control, Backups, Networking, Monitoring, SSH, Scripting, and Information Servers. Once you’ve mastered these hacks, you should absolutely read Linux Server Hacks, Volume Two, by William von Hagen and Brian Jones, which has 100 Linux hacks focussed on authentication, monitoring, security, performance and connectivity. 

# [http://www.amazon.com/gp/product/0596100574?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596100574 ][http://www.amazon.com/gp/product/0596100574?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596100574 DNS and BIND], by Cricket Liu and Paul Albitz'''. Several years ago, I''' '''configured my first DNS by reading online documentation. I brought this book to understand how DNS and BIND works. I’ve already upgraded this book twice when a newer edition was released. This should definitely be in your library, if you are a serious system administrator. 

# [http://www.amazon.com/gp/product/0596005652?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596005652 ][http://www.amazon.com/gp/product/0596005652?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596005652 Understanding the Linux Kernel], by Daniel Bovet and Marco Cesati. '''

If you are a serious developer on Linux environment or a sysadmin, this is a must read. This books explains the inner workings of the Linux Kernel 2.6 in a structured and logical way. This talks about how Kenel handles the Memory Management, Process scheduling, I/O architecture and Block devices. Overall this book is a treat for geeks who are curious to explore what is under the hood of Linux. 


# [http://www.amazon.com/gp/product/0596006403?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596006403 ][http://www.amazon.com/gp/product/0596006403?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596006403 Linux Cookbook], by Carla Schroder'''. This book covers Linux features''' '''from both users and system administrators point of view. There are 




two chapters dedicated for installing and managing software on RPM-based system and Debian. If you use RedHat, the Linux Pocket Guide, by Daniel J. Barrett is an excellent addition to your library, which covers all the essential Linux command with a sample usage.


# [http://www.amazon.com/gp/product/1593271417?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1593271417 ][http://www.amazon.com/gp/product/1593271417?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1593271417 Linux Firewalls], by Michael Rash'''. To build a secure Linux system,''' '''you must read this book. There are quiet few books out there for iptables. But, this one talks specifically about the fundamentals of how to configure an Intrusion Detection System using iptables, psad and fwsnort. If you want a comprehensive handy reference of all the things iptables can do with specific examples, Linux Iptables Pocket Reference, by Gregor N. Purdy is the best. 

# [http://www.amazon.com/gp/product/0131480049?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0131480049 ][http://www.amazon.com/gp/product/0131480049?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0131480049 Linux Administration Handbook], by Evi Nemeth, Garth Snyder and Trent R. Hein'''. During my early days of system administration, I’ve''' '''referred this book frequently. This is pretty detailed book with close to 1000 pages and 30 chapters that are nicely grouped together in three high level sections — Basic Administration, Networking and Bunch O’ Stuff. 

# [http://www.amazon.com/gp/product/1590599918?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1590599918 ][http://www.amazon.com/gp/product/1590599918?ie=UTF8&tag=thgest-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1590599918 Beginning Ubuntu Linux], by Keir Thomas and Jaime Sicam'''. For''' '''those who like to transition from Windows to Linux, install Ubuntu Linux on one of your old laptop or desktop and get this book. I strongly believe in spreading the news about Linux to those who don’t use it. If you want any of your loved ones or friends to learn Linux, install Ubuntu on an old laptop and give this book as a gift to them. They’ll definitely be very thankful to you. 



'''Extended Reading'''


Following are few articles from [http://www.thegeekstuff.com/ ][http://www.thegeekstuff.com/ The Geek Stuff][http://www.thegeekstuff.com/  ]blog for your extended reading. Check out [http://www.thegeekstuff.com/best-of-the-blog/ ][http://www.thegeekstuff.com/best-of-the-blog/ Best Of The Blog][http://www.thegeekstuff.com/best-of-the-blog/  ]section for more articles.


o [http://www.thegeekstuff.com/2008/08/turbocharge-putty-with-12-powerful-add-ons-software-for-geeks-3/ ][http://www.thegeekstuff.com/2008/08/turbocharge-putty-with-12-powerful-add-ons-software-for-geeks-3/ Turbocharge PuTTY with 12 Powerful Add-Ons] o Nagios - Enterprise Monitoring Solution


o [http://www.thegeekstuff.com/2008/05/nagios-30-jumpstart-guide-for-red-hat-overview-installation-and-configuration/ ][http://www.thegeekstuff.com/2008/05/nagios-30-jumpstart-guide-for-red-hat-overview-installation-and-configuration/ Nagios Jumpstart Guide]


o [http://www.thegeekstuff.com/2008/05/nagios-30-jumpstart-guide-for-red-hat-overview-installation-and-configuration/ ][http://www.thegeekstuff.com/2008/05/nagios-30-jumpstart-guide-for-red-hat-overview-installation-and-configuration/ Monitor Window Server]


o [http://www.thegeekstuff.com/2008/06/how-to-monitor-remote-linux-host-using-nagios-30/ ][http://www.thegeekstuff.com/2008/06/how-to-monitor-remote-linux-host-using-nagios-30/ Monitor Linux Server]


o [http://www.thegeekstuff.com/2008/11/how-to-monitor-network-switch-and-ports-using-nagios/ ][http://www.thegeekstuff.com/2008/11/how-to-monitor-network-switch-and-ports-using-nagios/ Monitor Network Switch]


o [http://www.thegeekstuff.com/2008/09/how-to-monitor-vpn-active-sessions-and-temperature-using-nagios/ ][http://www.thegeekstuff.com/2008/09/how-to-monitor-vpn-active-sessions-and-temperature-using-nagios/ Monitor VPN Device]


o Perform SSH and SCP without entering password: o [http://www.thegeekstuff.com/2008/06/perform-ssh-and-scp-without-entering-password-on-openssh/ ][http://www.thegeekstuff.com/2008/06/perform-ssh-and-scp-without-entering-password-on-openssh/ From openSSH to openSSH]


o [http://www.thegeekstuff.com/2008/07/ssh-key-based-authentication-setup-from-openssh-to-ssh2/ ][http://www.thegeekstuff.com/2008/07/ssh-key-based-authentication-setup-from-openssh-to-ssh2/ From openSSH to SSH2] o [http://www.thegeekstuff.com/2008/06/comprehensive-guide-for-ssh2-key-based-authentication-setup/ ][http://www.thegeekstuff.com/2008/06/comprehensive-guide-for-ssh2-key-based-authentication-setup/ From SSH2 to SSH2]

o [http://www.thegeekstuff.com/tag/vi-vim-tips-and-tricks/ ][http://www.thegeekstuff.com/tag/vi-vim-tips-and-tricks/ Vi / Vim Tips and Tricks]


o [http://www.thegeekstuff.com/2009/01/vi-and-vim-macro-tutorial-how-to-record-and-play/ ][http://www.thegeekstuff.com/2009/01/vi-and-vim-macro-tutorial-how-to-record-and-play/ Vim Macro Tutorial: How To Record and Play] o How To Use Vim as [http://www.thegeekstuff.com/2009/01/make-vim-as-your-perl-ide-using-perl-supportvim-plugin/ ][http://www.thegeekstuff.com/2009/01/make-vim-as-your-perl-ide-using-perl-supportvim-plugin/ Perl IDE][http://www.thegeekstuff.com/2009/01/make-vim-as-your-perl-ide-using-perl-supportvim-plugin/  ]and [http://www.thegeekstuff.com/2009/01/tutorial-make-vim-as-your-cc-ide-using-cvim-plugin/ ][http://www.thegeekstuff.com/2009/01/tutorial-make-vim-as-your-cc-ide-using-cvim-plugin/ C/C++ IDE] o [http://www.thegeekstuff.com/2009/01/vi-and-vim-editor-5-awesome-examples-for-automatic-word-completion-using-ctrl-x-magic/ ][http://www.thegeekstuff.com/2009/01/vi-and-vim-editor-5-awesome-examples-for-automatic-word-completion-using-ctrl-x-magic/ Automatic Word Completion in Vim]


o [http://www.thegeekstuff.com/2008/12/vi-and-vim-autocommand-3-steps-to-add-custom-header-to-your-file/ ][http://www.thegeekstuff.com/2008/12/vi-and-vim-autocommand-3-steps-to-add-custom-header-to-your-file/ 3 Steps to Add Custom Header to a File Using Vim] o [http://www.thegeekstuff.com/2008/06/the-ultimate-guide-for-creating-strong-passwords/ ][http://www.thegeekstuff.com/2008/06/the-ultimate-guide-for-creating-strong-passwords/ The Ultimate Guide for Creating Strong Passwords]


# [http://www.thegeekstuff.com/2008/09/hire-7-personal-bodyguards-to-browse-internet-securely/ ][http://www.thegeekstuff.com/2008/09/hire-7-personal-bodyguards-to-browse-internet-securely/ Firefox Add-On: Hire 7 Personal Bodyguards to Browse Internet] Securely 

o [http://www.thegeekstuff.com/2008/12/tripwire-tutorial-linux-host-based-intrusion-detection-system/ ][http://www.thegeekstuff.com/2008/12/tripwire-tutorial-linux-host-based-intrusion-detection-system/ Tripwire Tutorial: Linux Host Based Intrusion Detection System]


# [http://www.thegeekstuff.com/2008/10/midnight-commander-mc-guide-powerful-text-based-file-manager-for-unix/ ][http://www.thegeekstuff.com/2008/10/midnight-commander-mc-guide-powerful-text-based-file-manager-for-unix/ Midnight Commander (mc) Guide: Powerful Text based File ][http://www.thegeekstuff.com/2008/10/midnight-commander-mc-guide-powerful-text-based-file-manager-for-unix/ Manager] [http://www.thegeekstuff.com/2008/10/midnight-commander-mc-guide-powerful-text-based-file-manager-for-unix/ ][http://www.thegeekstuff.com/2008/10/midnight-commander-mc-guide-powerful-text-based-file-manager-for-unix/ for Unix] 



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