Summery
日時の表示、設定を行う。Construction
$ date
Option
-s : 時刻をセットする + : フォーマット指定
Sample
# 現在時刻の表示
$ date
# 日時の表示フォーマットを変更する
$ date +"%Y/%m/%d %p %I:%M:%S"
# 時刻をセットする
$ date -s "03/15 14:30 2015"
# 日付を表示 yyyymmdd
$ date +%Y%m%d
# 時刻を表示 hhiiss
$ date +%k%M%S
Discription
NAME
date -- display or set date and time
SYNOPSIS
date [-ju] [-r seconds] [-v [+|-]val[ymwdHMS]] ... [+output_fmt]
date [-jnu] [[[mm]dd]HH]MM[[cc]yy][.ss]
date [-jnu] -f input_fmt new_date [+output_fmt]
date [-d dst] [-t minutes_west]
DESCRIPTION
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.
The date utility displays the date and time read from the kernel clock. When
used to set the date and time, both the kernel clock and the hardware clock
are updated.
Only the superuser may set the date, and if the system securelevel (see
securelevel(8)) is greater than 1, the time may not be changed by more than 1
second.
The options are as follows:
-d dst Set the kernel's value for daylight saving time. If dst is non-zero,
future calls to gettimeofday(2) will return a non-zero for tz_dsttime.
-f Use input_fmt as the format string to parse the new_date provided
rather than using the default [[[mm]dd]HH]MM[[cc]yy][.ss] format.
Parsing is done using strptime(3).
-j Do not try to set the date. This allows you to use the -f flag in
addition to the + option to convert one date format to another.
-n By default, if the timed(8) daemon is running, date sets the time on
all of the machines in the local group. The -n option suppresses this
behavior and causes the time to be set only on the current machine.
-r seconds
Print the date and time represented by seconds, where seconds is the
number of seconds since the Epoch (00:00:00 UTC, January 1, 1970; see
time(3)), and can be specified in decimal, octal, or hex.
-t minutes_west
Set the system's value for minutes west of GMT. minutes_west speci-
fies 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.
-v Adjust (i.e., take the current date and display the result of the
adjustment; not actually set the date) the second, minute, hour, month
day, week day, month or year according to val. If val is preceded
with a plus or minus sign, the date is adjusted forwards or backwards
according to the remaining string, otherwise the relevant part of the
date is set. The date can be adjusted as many times as required using
these flags. Flags are processed in the order given.
When setting values (rather than adjusting them), seconds are in the
range 0-59, minutes are in the range 0-59, hours are in the range
0-23, month days are in the range 1-31, week days are in the range 0-6
(Sun-Sat), months are in the range 1-12 (Jan-Dec) and years are in the
range 80-38 or 1980-2038.
If val is numeric, one of either y, m, w, d, H, M or S must be used to
specify which part of the date is to be adjusted.
The week day or month may be specified using a name rather than a num-
ber. If a name is used with the plus (or minus) sign, the date will
be put forwards (or backwards) to the next (previous) date that
matches the given week day or month. This will not adjust the date,
if the given week day or month is the same as the current one.
When a date is adjusted to a specific value or in units greater than
hours, daylight savings time considerations are ignored. Adjustments
in units of hours or less honor daylight saving time. So, assuming
the current date is March 26, 0:30 and that the DST adjustment means
that the clock goes forward at 01:00 to 02:00, using -v +1H will
adjust the date to March 26, 2:30. Likewise, if the date is October
29, 0:30 and the DST adjustment means that the clock goes back at
02:00 to 01:00, using -v +3H will be necessary to reach October 29,
2:30.
When the date is adjusted to a specific value that does not actually
exist (for example March 26, 1:30 BST 2000 in the Europe/London time-
zone), the date will be silently adjusted forwards in units of one
hour until it reaches a valid time. When the date is adjusted to a
specific value that occurs twice (for example October 29, 1:30 2000),
the resulting timezone will be set so that the date matches the ear-
lier of the two times.
Adjusting the date by months is inherently ambiguous because a month
is a unit of variable length depending on the current date. This kind
of date adjustment is applied in the most intuitive way. First of
all, date tries to preserve the day of the month. If it is impossible
because the target month is shorter than the present one, the last day
of the target month will be the result. For example, using -v +1m on
May 31 will adjust the date to June 30, while using the same option on
January 30 will result in the date adjusted to the last day of Febru-
ary. This approach is also believed to make the most sense for shell
scripting. Nevertheless, be aware that going forth and back by the
same number of months may take you to a different date.
Refer to the examples below for further details.
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:
cc Century (either 19 or 20) prepended to the abbreviated year.
yy Year in abbreviated form (e.g., 89 for 1989, 06 for 2006).
mm Numeric month, a number from 1 to 12.
dd Day, a number from 1 to 31.
HH Hour, a number from 0 to 23.
MM Minutes, a number from 0 to 59.
ss Seconds, a number from 0 to 61 (59 plus a maximum of two leap
seconds).
Everything but the minutes is optional.
Time changes for Daylight Saving Time, standard time, leap seconds, and leap
years are handled automatically.
ENVIRONMENT
The following environment variables affect the execution of date:
TZ The timezone to use when displaying dates. The normal format is a
pathname relative to /usr/share/zoneinfo. For example, the command
``TZ=America/Los_Angeles date'' displays the current time in Califor-
nia. See environ(7) for more information.
FILES
/var/log/messages record of the user setting the time
EXIT STATUS
The date utility exits 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.
EXAMPLES
The command:
date "+DATE: %Y-%m-%d%nTIME: %H:%M:%S"
will display:
DATE: 1987-11-21
TIME: 13:36:16
In the Europe/London timezone, the command:
date -v1m -v+1y
will display:
Sun Jan 4 04:15:24 GMT 1998
where it is currently Mon Aug 4 04:15:24 BST 1997.
The command:
date -v1d -v3m -v0y -v-1d
will display the last day of February in the year 2000:
Tue Feb 29 03:18:00 GMT 2000
So will do the command:
date -v30d -v3m -v0y -v-1m
because there is no such date as the 30th of February.
The command:
date -v1d -v+1m -v-1d -v-fri
will display the last Friday of the month:
Fri Aug 29 04:31:11 BST 1997
where it is currently Mon Aug 4 04:31:11 BST 1997.
The command:
date 0613162785
sets the date to ``June 13, 1985, 4:27 PM''.
date "+%m%d%H%M%Y.%S"
may be used on one machine to print out the date suitable for setting on
another.
The command:
date 1432
sets the time to 2:32 PM, without modifying the date.
Finally the command:
date -j -f "%a %b %d %T %Z %Y" "`date`" "+%s"
can be used to parse the output from date and express it in Epoch time.
DIAGNOSTICS
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(8) fails.
LEGACY SYNOPSIS
As above, except for the second line, which is:
date [-jnu] [[[[[cc]yy]mm]dd]HH]MM[.ss]
LEGACY DIAGNOSTICS
When invoked in legacy mode, the following exit values are returned:
0 The date was written successfully
1 Unable to set the date
2 Able to set the local date, but unable to set it globally
For more information about legacy mode, see compat(5).
SEE ALSO
gettimeofday(2), strftime(3), strptime(3), utmpx(5), timed(8)
R. Gusella and S. Zatti, TSP: The Time Synchronization Protocol for UNIX
4.3BSD.
STANDARDS
The date utility is expected to be compatible with IEEE Std 1003.2
(``POSIX.2'').
HISTORY
A date command appeared in Version 1 AT&T UNIX.
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