date —
display or set date and time
date |
[ -aju
]
[-d
dst
]
[-r
seconds
]
[-t
minutes_west
]
[-z
output_zone
]
[+format
]
[] |
When invoked without arguments, the
date
utility displays the current date and time. Otherwise, depending on the
options specified,
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:
-
-
-a- Use the
adjtime(2) call
to gradually skew the local time to the desired time rather than just
hopping.
-
-
-d
dst- Set the system's value for Daylight Saving Time. If
dst is non-zero, future calls to
gettimeofday(2)
will return a non-zero value for
tz_dsttime.
-
-
-j- Parse the provided date and time and display the result without changing
the clock.
-
-
-r
seconds- Print out (in specified format) the date and time represented by
seconds from the Epoch.
-
-
-t
minutes_west- Set the system's value for minutes west of GMT.
minutes_west specifies the number of
minutes returned in tz_minuteswest by
future calls to
gettimeofday(2).
-
-
-u- Display or set the date in UTC (Coordinated Universal) time.
-
-
-z
output_zone- Just before printing the time, change to the specified timezone; see the
description of
TZ below. This can be
used with -j to 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:
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:
- ccyy
- 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.
- mm
- Month: a number from 1 to 12.
- dd
- Day: a number from 1 to 31.
- HH
- Hour: a number from 0 to 23.
- MM
- Minute: a number from 0 to 59.
- SS
- 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.
-
-
TZ- The time zone to use when parsing or displaying dates. See
environ(7) for
more information. If this variable is not set, the time zone is determined
based on /etc/localtime, which the
administrator adjusts using the
-l
option of
zic(8).
- /var/log/wtmp
- record of date resets and time changes
- /var/log/messages
- record of the user setting the time
The
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
adjtime(2),
gettimeofday(2),
strftime(3),
utmp(5),
ntpd(8),
rdate(8)
The
date utility is compliant with the
IEEE Std 1003.1-2008
(“POSIX.1”) specification.
The flags [
-adjrtz
], as
well as the conversion specifiers ‘
%F’,
‘
%G’,
‘
%g’,
‘
%k’,
‘
%l’,
‘
%R’,
‘
%s’,
‘
%v’, and
‘
%+’, are extensions to that
specification.
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.
A
date command appeared in
Version 1 AT&T UNIX.
![[OpenBSD]](/openbsd.gif){kind=small}