date的命令

date [option] [+fomat]


[option] 最常用的是-d 参数，这个参数指定了日期和时间 使用方法是 -d "str"
str有很多的方式，比如可以是 one day ago 等等
我最近使用的是这样的str
1970-01-01 86400 sec
意思是从1970-1-1开始，86400后的时间
可以从1970-8-9号开始， 可以是day..... 
str非常强大，以至于现在能想到的都有！！！！！！！！！！！！！！！！！！！！




在使用-d参数指定时间后，可以用+指定输出格式如
 %%     a literal %


       %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  3 23:05:25 2005)


       %C     century; like %Y, except omit last two digits (e.g., 20)


       %d     day of month (e.g, 01)


       %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 (00..23)


       %I     hour (01..12)


       %j     day of year (001..366)


       %k     hour ( 0..23)


       %l     hour ( 1..12)


       %m     month (01..12)


       %M     minute (00..59)


       %n     a newline


       %N     nanoseconds (000000000..999999999)


       %p     locale's equivalent of either AM or PM; blank if not known


       %P     like %p, but lower case


       %r     locale's 12-hour clock time (e.g., 11:11:04 PM)


       %R     24-hour hour and minute; same as %H:%M


       %s     seconds since 1970-01-01 00:00:00 UTC


       %S     second (00..60)


       %t     a tab


       %T     time; same as %H:%M:%S


       %u     day of week (1..7); 1 is Monday


       %U     week number of year, with Sunday as first day of week (00..53)


       %V     ISO week number, with Monday as first day of week (01..53)


       %w     day of week (0..6); 0 is Sunday


       %W     week number of year, with Monday as first day of week (00..53)


       %x     locale's date representation (e.g., 12/31/99)


       %X     locale's time representation (e.g., 23:13:48)


       %y     last two digits of year (00..99)


       %Y     year


       %z     +hhmm numeric timezone (e.g., -0400)


       %:z    +hh:mm numeric timezone (e.g., -04:00)


       %::z   +hh:mm:ss numeric time zone (e.g., -04:00:00)


       %:::z  numeric time zone with : to necessary precision (e.g., -04, +05:30)


       %Z     alphabetic time zone abbreviation (e.g., EDT)