NAME
date
- display or set date and time
SYNOPSIS
date
[-ajnu]
[-d date]
[-r seconds]
[+format]
yy]
mm]
dd]
[HH MM ]
.
SS[[[[[[CC]]]
DESCRIPTION
date
displays the current date and time when invoked without arguments.
Providing arguments will format the date and time in a user-defined
way or set the date.
Only the superuser may set the date.
The options are as follows:
- -a
-
Use
adjtime(2)
to change the local system time slowly,
maintaining it as a monotonically increasing function.
-a
implies
-n.
- -d date
-
Parse the provided human-described date and time and display the result without
actually changing the system clock.
- -j
-
Parse the provided canonical representation of date and time (described below)
and display the result without actually changing the system clock.
- -n
-
The utility
timed(8)
is used to synchronize the clocks on groups of machines.
By default, if
timed
is running,
date
will set the time on all of the machines in the local group.
The
-n
option stops
date
from setting the time for other than the current machine.
- -r
-
Print out the date and time that is
seconds
from the Epoch.
- -u
-
Display or set the date in
UTC
(universal) time.
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> 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:
- CC
-
The first two digits of the year (the century).
- yy
-
The second two digits of the 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
-
The month of the year, from 01 to 12.
- dd
-
The day of the month, from 01 to 31.
- HH
-
The hour of the day, from 00 to 23.
- MM
-
The minute of the hour, from 00 to 59.
- SS
-
The second of the minute, from 00 to 61.
Everything but the minutes is optional.
Time changes for Daylight Saving and Standard time and leap seconds
and years are handled automatically.
ENVIRONMENT
The following environment variables affect the execution of
:
TZ
-
The timezone to use when displaying dates.
See
environ(7)
for more information.
FILES
/etc/localtime
-
Symlink pointing to system's default timezone information file in
/usr/share/zoneinfo
directory.
/var/log/wtmp
-
A record of date resets and time changes.
/var/log/messages
-
A record of the user setting the time.
EXAMPLES
The command:
-
date '+DATE: %m/%d/%y%nTIME: %H:%M:%S'
will display:
-
DATE: 11/21/87
TIME: 13:36:16
The command:
-
date 8506131627
sets the date to
``
June 13, 1985, 4:27 PM
''.
The command:
-
date 1432
sets the time to
2:32 PM
,
without modifying the date.
DIAGNOSTICS
Exit status is 0 on success, 1 if unable to set the date, and 2
if able to set the local date, but unable to set it globally.
Occasionally, when
timed(8)
synchronizes the time on many hosts, the setting of a new time value may
require more than a few seconds.
On these occasions,
date
prints:
`Network time being set'.
The message
`Communication error with timed'
occurs when the communication
between
date
and
timed
fails.
SEE ALSO
adjtime(2),
gettimeofday(2),
settimeofday(2),
parsedate(3),
strftime(3),
utmp(5),
timed(8)
STANDARDS
The
date
utility is expected to be compatible with
IEEE Std 1003.2 (``POSIX.2'') .