display or set date and time
When invoked without arguments, the
utility displays the current date and time. Otherwise, depending on the
date will set the date and time
or print it in a user-defined way.
Changing the system date has some risks, as described in settimeofday(2). Only the superuser may change the date.
The options are as follows:
- Use the adjtime(2) call to gradually skew the local time to the desired time rather than just hopping.
- Parse the specified time using strptime(3) with a format string of pformat.
- Parse the provided date and time and display the result without changing the clock.
- Print out (in specified format) the date and time represented by seconds from the Epoch.
- Display or set the date in UTC (Coordinated Universal) time.
- Just before printing the time, change to the specified timezone; see the
TZbelow. This can be used with
-jto easily convert time specifications from one zone to another.
An operand with a leading plus sign (‘+’) signals a
user-defined format string which specifies the format in which to display
the date and time. The format string may contain any of the conversion
specifications described in the
strftime(3) manual page, as well as any arbitrary text. A newline
\n’) character is always output
after the characters specified by the format string. The format string for
the default display is:
%a %b %e %H:%M:%S %Z %Y
If an operand does not have a leading plus sign, it is interpreted as a value for setting the system's notion of the current date and time. The canonical representation for setting the date and time is:
- Year. If yy is specified, but cc is not, a value for yy between 69 and 99 results in a cc value of 19. Otherwise, a cc value of 20 is used.
- Month: a number from 1 to 12.
- Day: a number from 1 to 31.
- Hour: a number from 0 to 23.
- Minute: a number from 0 to 59.
- Second: a number from 0 to 60 (permitting a leap second), preceded by a period.
Everything but the minute is optional.
Time changes for Daylight Saving Time, standard time, leap seconds, and leap years are handled automatically.
- The time zone to use when parsing or displaying dates. It is normally
specified as a pathname relative to
/usr/share/zoneinfo, though see
tzset(3) for more information. If this variable is not set, the
time zone is determined based on /etc/localtime,
which the administrator adjusts using the
-loption of zic(8).
- record of date resets and time changes
- record of the user setting the time
date utility exits 0 on
success, and >0 if an error occurs.
Display the date using the specified format string:
$ date "+DATE: %Y-%m-%d%nTIME: %H:%M:%S" DATE: 1987-11-21 TIME: 13:36:16
Set the date to June 13, 1985, 4:27 PM:
# date 198506131627
Set the time to 2:32 PM, without modifying the date:
# date 1432
If the mailing list server located in California is being taken offline at 5:45 AM, work out what time it will be locally, here in Tokyo:
$ TZ=America/Los_Angeles date -j -z Asia/Tokyo 0545
adjtime(2), gettimeofday(2), strftime(3), utmp(5), ntpd(8), rdate(8)
date utility is compliant with the
IEEE Std 1003.1-2008 (“POSIX.1”)
The flags [
-afjrz], as well as the
conversion specifiers ‘
%+’, are extensions to that
This implementation requires the traditional BSD date format, [[[[[cc]yy]mm]dd]HH]MM[.SS], which differs from the X/Open System Interfaces option of the IEEE Std 1003.1-2008 (“POSIX.1”) specification.
date command appeared in
Version 1 AT&T UNIX.