date --help

`date --help`命令用于显示Linux系统上`date`命令的帮助信息和可用选项。以下是`date --help`命令的输出：

Usage: date [OPTION]... [+FORMAT]
  or:  date [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]
Display the current time in the given FORMAT, or set the system date.
Formatting:
  %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, space padded ( 0..23); same as %_H
  %l    hour, space padded ( 1..12); same as %_I
  %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    alphabetic time zone abbreviation (e.g., EDT)
By default, date pads numeric fields with zeroes.  The following optional
flags may follow '%':
  -  (hyphen) do not pad the field
  _  (underscore) pad with spaces
  0  (zero) pad with zeros
  ^  use upper case if possible
  #  use opposite case if possible
After any flags comes an optional field width, as a decimal number; then
an optional modifier, which is either E to use the locale's alternate
representations if available, or O to use the locale's alternate numeric
symbols if available.

该命令列出了`date`命令支持的所有选项和格式化选项，可以帮助您更好地了解如何使用该命令。