date命令说明

基本使用格式：

date [-d "time-to-display"] +"format-to-display"

-d指定要显示的时间，如果不指定默认为当前时间；后边的+后的字符串为指定的输出格式，类式C的print的格式。常用示例如下：

date -d "1 day ago" +"%Y-%m-%d"
date -d "30 day ago" +"%Y-%m-%d"
date -d "+ 1 day" +"%Y-%m-%d"
date -d "- 1 month" +"%Y-%m-%d"
date -d "" +"%Y-%m-%d"
date -d "" +"输出为：%Y-%m-%d"

支持的输出项：

       %a     locale’s abbreviated weekday name (e.g., Sun)
 
       %A     locale’s full weekday name (e.g., Sunday)
 
       %b     locale’s abbreviated month name (e.g., Jan)
 
       %B     locale’s full month name (e.g., January)
 
       %c     locale’s date and time (e.g., Thu Mar   :: )
 
       %C     century; like %Y, except omit last two digits (e.g., )
 
       %d     day of month (e.g, )
 
       %D     date; same as %m/%d/%y
 
       %e     day of month, space padded; same as %_d
 
       %F     full date; same as %Y-%m-%d
 
       %g     last two digits of year of ISO week number (see %G)
 
       %G     year of ISO week number (see %V); normally useful only with %V
 
       %h     same as %b
 
       %H     hour (..)
 
       %I     hour (..)
 
       %j     day of year (..)
 
       %k     hour ( ..)
       %l     hour ( ..)
 
       %m     month (..)
 
       %M     minute (..)
 
       %n     a newline
 
       %N     nanoseconds (..)
 
       %p     locale’s equivalent of either AM or PM; blank if not known
 
       %P     like %p, but lower case
 
       %r     locale’s -hour clock time (e.g., :: PM)
 
       %R     -hour hour and minute; same as %H:%M
 
       %s     seconds since -- :: UTC
 
       %S     second (..)
 
       %t     a tab
 
       %T     time; same as %H:%M:%S
 
       %u     day of week (..);  is Monday
 
       %U     week number of year, with Sunday as first day of week (..)
 
       %V     ISO week number, with Monday as first day of week (..)
 
       %w     day of week (..);  is Sunday
 
       %W     week number of year, with Monday as first day of week (..)
 
       %x     locale’s date representation (e.g., //)
 
       %X     locale’s time representation (e.g., ::)
 
       %y     last two digits of year (..)
 
       %Y     year
 
       %z     +hhmm numeric timezone (e.g., -)
 
       %:z    +hh:mm numeric timezone (e.g., -:)
 
       %::z   +hh:mm:ss numeric time zone (e.g., -::)
 
       %:::z  numeric time zone with : to necessary precision (e.g., -, +:)
 
       %Z     alphabetic time zone abbreviation (e.g., EDT)