Tribblix: manual page: date.1

DATE(1) User Commands DATE(1)

NAME

date - write the date and time

SYNOPSIS

/usr/bin/date [-u] [-r seconds | filename] [-R] [+format]

/usr/bin/date [-a [-]sss.fff]

/usr/bin/date [-u] [ [mmdd] HHMM | mmddHHMM [cc] yy] [.SS]

/usr/xpg4/bin/date [-u] [-r seconds | filename] [-R] [+format]

/usr/xpg4/bin/date [-a [-]sss.fff]

/usr/xpg4/bin/date [-u]
[ [mmdd] HHMM | mmddHHMM [cc] yy] [.SS]

DESCRIPTION

The date utility writes the date and time to standard output or
attempts to set the system date and time. By default, the current
date and time is written.

Specifications of native language translations of month and weekday
names are supported. The month and weekday names used for a language
are based on the locale specified by the environment variable
LC_TIME. See environ(7).

The following is the default form for the "C" locale:

%a %b %e %T %Z %Y

For example,

Fri Dec 23 10:10:42 EST 1988

OPTIONS

The following options are supported:

-a [-]sss.fff
Slowly adjust the time by sss.fff seconds
(fff represents fractions of a second). This
adjustment can be positive or negative. The
system's clock is sped up or slowed down
until it has drifted by the number of seconds
specified. Only the super-user may adjust the
time.

-r seconds
Rather than using the current time, obtain
the time based on seconds. seconds will be
treated as time since the UNIX Epoch
(00:00:00 UTC, January 1, 1970).

-r filename
Rather than using the current time, obtain
the time based on the modification time of
filename.

-R
Change the default format to the format used
for mail message headers (similar to RFC 822
format). The default format becomes

%a, %d %h %Y %H:%M:%S %z

-u
Display (or set) the date in Greenwich Mean
Time (GMT--universal time), bypassing the
normal conversion to (or from) local time.

OPERANDS

The following operands are supported:

+format
If the argument begins with +, the output of date is the
result of passing format and the current time to
strftime(). date uses the conversion specifications
listed on the strftime(3C) manual page, with the
conversion specification for %C determined by whether
/usr/bin/date or /usr/xpg4/bin/date is used:

/usr/bin/date
Locale's date and time
representation. This is the
default output for date.

/usr/xpg4/bin/date
Century (a year divided by 100 and
truncated to an integer) as a
decimal number [00-99].

In addition, the nonstandard conversion specification %N
is also supported, and is converted to the zero-padded
number of nanoseconds since the last second. Note that
the actual resolution of this number is limited to the
resolution of the system's CLOCK_REALTIME clock. See
clock_gettime(3C).

The string is always terminated with a NEWLINE. An
argument containing blanks must be quoted; see the
EXAMPLES section.

mm
Month number

dd
Day number in the month

HH
Hour number (24 hour system)

MM
Minute number

SS
Second number

cc
Century (a year divided by 100 and truncated to an
integer) as a decimal number [00-99]. For example, cc is
19 for the year 1988 and 20 for the year 2007.

yy
Last two digits of the year number. If century (cc) is
not specified, then values in the range 69-99 shall refer
to years 1969 to 1999 inclusive, and values in the range
00-68 shall refer to years 2000 to 2068, inclusive.

The month, day, year number, and century may be omitted; the current
values are applied as defaults. For example, the following entry:

example% date 10080045

sets the date to Oct 8, 12:45 a.m. The current year is the default
because no year is supplied. The system operates in GMT. date takes
care of the conversion to and from local standard and daylight time.
Only the super-user may change the date. After successfully setting
the date and time, date displays the new date according to the
default format. The date command uses TZ to determine the correct
time zone information; see environ(7).

EXAMPLES

Example 1: Generating Output

The following command:

example% date '+DATE: %m/%d/%y%nTIME:%H:%M:%S'

generates as output

DATE: 08/01/76

TIME: 14:45:05

Example 2: Setting the Current Time

The following command sets the current time to 12:34:56:

example# date 1234.56

Example 3: Setting Another Time and Date in Greenwich Mean Time

The following command sets the date to January 1st, 12:30 am, 2000:

example# date -u 010100302000

This is displayed as:

Thu Jan 01 00:30:00 GMT 2000

ENVIRONMENT VARIABLES

See environ(7) for descriptions of the following environment
variables that affect the execution of date: LANG, LC_ALL, LC_CTYPE,
LC_TIME, LC_MESSAGES, and NLSPATH.

TZ
Determine the timezone in which the time and date are written,
unless the -u option is specified. If the TZ variable is not
set and the -u is not specified, the system default timezone
is used.

EXIT STATUS

The following exit values are returned:

0
Successful completion.

>0
An error occurred.

ATTRIBUTES

DIAGNOSTICS

no permission
You are not the super-user and you tried to change
the date.

bad conversion
The date set is syntactically incorrect.

NOTES

If you attempt to set the current date to one of the dates that the
standard and alternate time zones change (for example, the date that
daylight time is starting or ending), and you attempt to set the time
to a time in the interval between the end of standard time and the
beginning of the alternate time (or the end of the alternate time and
the beginning of standard time), the results are unpredictable.

Using the date command from within windowing environments to change
the date can lead to unpredictable results and is unsafe. It can also
be unsafe in the multi-user mode, that is, outside of a windowing
system, if the date is changed rapidly back and forth. The
recommended method of changing the date is 'date -a'.

Setting the system time or allowing the system time to progress
beyond 03:14:07 UTC Jan 19, 2038 is not supported on Solaris.

December 6, 2017 DATE(1)