A date explanation under Linux

Date: View or modify the system date time

Date [OPTION] ... [+format]
Date [-u|--utc|--universal] [MMDDHHMM[[CC]YY][.SS]]

-d,--date= string: The string is entered as a date, not the current time nor the current time setting

Example: [[email protected]/]# date-d 212223
Date:invalid Date ' 212223 '
[Email protected]/]# date-d 2122
Thu 21:22:00 PDT 2015
[Email protected]/]# date-d 21
Thu 21:00:00 PDT 2015
[Email protected]/]# date-d 21222
Date:invalid Date ' 21222 '

[Email protected]/]# date-d 212
Thu 02:12:00 PDT 2015

Summary: A string in-D string can only be 4 digits in number, and can only be changed to hours minutes, hours takes precedence over minutes

-R--reference=file: Lists the last modification time of the following files

Example: [[email protected] tmp]# Date
Thu 07:33:16 PDT 2015
[Email protected] tmp]# date-r
Thu, 2015 07:33:19-0700

-S--set=string: Sets the system time to STRING description

Example: [[email protected] tmp]# Date
Thu 07:36:49 PDT 2015
[Email protected] tmp]# date-s 2237
Thu 22:37:00 PDT 2015
[[Email protected] tmp]# Date
Thu 22:37:03 PDT 2015

-U--utc--universal: View or modify Standard Time

+format:

     %%   a literal%
      %a    Show Current week
      %A    show current week   full name
      %b    Displays the current month, abbreviated
     %b    Displays the current month, full name
       %c    Show Current time
      %C    show current century
      %d    Current date is the day of the current month
     %d     Displays the current date, the display format is  %m/%d/%y (08/20/15)
      %F    Displays the full date; format is%y-% m-%d (2015-08-20)  
     %h    Show Current hour (24-hour)  %k can also achieve this effect
     %i    Displays the current hour (12 hour)   %l can also achieve this effect

%j display date is the first day of the Year in China
%m show it as the first month
%M display the current number of minutes
%r display the current time in 12 hours
%R shows the current hour minute format as%h:%m (22:55)
%s number of seconds since 1970-01-01
%s Displays the current time description
%T Displays the current time, with the time format%h:%m:%s (22:59:57)
%u represents the number of weeks by number; 1 is monday,1-7,7 to Sunday
%w the number of weeks in numbers; 0 is sunday,6 to Saturday
%x displays local time in the time format (12/31/99)
%x displays local time in the format (23:13:48)
%Y Year Displays current years

A date explanation under Linux