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='''Chapter 2: Date Manipulation'''= =='''Hack 7. Set System Date and Time'''== To change the system date use: <nowiki># </nowiki>date {mmddhhmiyyyy.ss} o mm – Month o dd – Date o hh – 24 hour format o mi – Minutes o yyyy – Year o ss – seconds For example, to set system date to Jan 31<sup>st</sup> 2008, 10:19 p.m, 53 seconds <nowiki># </nowiki>date 013122192009.53 You can also change system date using set argument as shown below. # date 013122192009.53 # date +%Y%m%d -s "20090131" # date -s "01/31/2009 22:19:53" # date -s "31 JAN 2009 22:19:53" # date set="31 JAN 2009 22:19:53" To set the time only: <nowiki># </nowiki>date +%T -s "22:19:53" <nowiki># </nowiki>date +%T%p -s "10:19:53PM" =='''Hack 8. Set Hardware Date and Time'''== Before setting the hardware date and time, make sure the OS date and time is set appropriately as shown in the hack#7. Set the hardware date and time based on the system date as shown below: # hwclock –systohc # hwclock --systohc –utc Use hwclock without any parameter, to view the current hardware date and time: <nowiki># </nowiki>hwclock Check the clock file to verify whether the system is set for UTC: <nowiki># </nowiki>cat /etc/sysconfig/clock ZONE="America/Los_Angeles" UTC=false ARC=false =='''Hack 9. Display Current Date and Time in a Specific'''== '''Format''' Following are different ways of displaying the current date and time in various formats: $ date Thu Jan 1 08:19:23 PST 2009 $ date --date="now" Thu Jan 1 08:20:05 PST 2009 $ date --date="today" Thu Jan 1 08:20:12 PST 2009 $ date --date='1970-01-01 00:00:01 UTC +5 hours' +%s 18001 $ date '+Current Date: %m/%d/%y%nCurrent Time:%H:%M:%S' Current Date: 01/01/09 Current Time:08:21:41 $ date +"%d-%m-%Y" 01-01-2009 $ date +"%d/%m/%Y" 01/01/2009 $ date +"%A,%B %d %Y" Thursday,January 01 2009 Following are the different format options you can pass to the date command: {| style="border-spacing:0;" | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| o | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| %D | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| date (mm/dd/yy) |- | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| o | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| %d | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| day of month (01..31) |- | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| o | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| %m | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| month (01..12) |- | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| o | colspan="2" style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| %y last two digits of year (00..99) |- | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| o | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| %a | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| locale’s abbreviated weekday name (Sun..Sat) |} # %A locale’s full weekday name, variable length (Sunday..Saturday) o %b locale’s abbreviated month name (Jan..Dec) # %B locale’s full month name, variable length (January..December) {| style="border-spacing:0;" | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| o | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| %H | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| hour (00..23) |- | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| o | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| %I | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| hour (01..12) |- | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| o | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| %Y | style="border:none;padding-top:0in;padding-bottom:0in;padding-left:0.075in;padding-right:0.075in;"| year (1970…) |} =='''Hack 10. Display Past Date and Time'''== Following are various ways to display a past date and time: $ date --date='3 seconds ago' Thu Jan 1 08:27:00 PST 2009 $ date --date="1 day ago" Wed Dec 31 08:27:13 PST 2008 $ date --date="1 days ago" Wed Dec 31 08:27:18 PST 2008 $ date --date="1 month ago" Mon Dec 1 08:27:23 PST 2008 $ date --date="1 year ago" Tue Jan 1 08:27:28 PST 2008 $ date --date="yesterday" Wed Dec 31 08:27:34 PST 2008 $ date --date="10 months 2 day ago" Thu Feb 28 08:27:41 PST 2008 =='''Hack 11. Display Future Date and Time'''== Following examples shows how to display a future date and time. $ date Thu Jan 1 08:30:07 PST 2009 $ date --date='3 seconds' Thu Jan 1 08:30:12 PST 2009 $ date --date='4 hours' Thu Jan 1 12:30:17 PST 2009 $ date --date='tomorrow' Fri Jan 2 08:30:25 PST 2009 $ date --date="1 day" Fri Jan 2 08:30:31 PST 2009 $ date --date="1 days" Fri Jan 2 08:30:38 PST 2009 $ date --date="2 days" Sat Jan 3 08:30:43 PST 2009 $ date --date='1 month' Sun Feb 1 08:30:48 PST 2009 $ date --date='1 week' Thu Jan 8 08:30:53 PST 2009 $ date --date="2 months" Sun Mar 1 08:30:58 PST 2009 $ date --date="2 years" Sat Jan 1 08:31:03 PST 2011 $ date --date="next day" Fri Jan 2 08:31:10 PST 2009 $ date --date="-1 days ago" Fri Jan 2 08:31:15 PST 2009 $ date --date="this Wednesday" Wed Jan 7 00:00:00 PST 2009
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