date(1) General Commands Manual date(1)
NAME
date - Displays or sets the date
SYNOPSIS
Without Superuser Authority - Displays the Date
date [-u] [+field_descriptor ...]
With Superuser Authority - Sets the Date
date [-nu] [MMddhhmm.ssyy | alternate_date_format] [+field_descriptor ...]
Using XCU5.0 - Sets or Displays the Date
date [-u] mmddHHMM[yy]
date [-u] [+field_descriptor ...]
Using the Century Field Provided by Compaq - Sets the Date
date mmddHHMM[[cc]yy] [.ss]
date [[cc]yy]mmddHHMM[.ss]
date mmddHHMM[.ss[[cc]yy]]
STANDARDS
Interfaces documented on this reference page conform to industry standards as follows:
date: XCU5.0
Refer to the standards(5) reference page for more information about industry standards and associated tags.
OPTIONS
[Tru64 UNIX] Does not set the time globally on all machines in a local area network that have their clocks synchronized (superuser only).
Performs operations as if the TZ environment variable was set to the string GMT0. Otherwise, date uses the time zone indicated by the TZ
environment variable or the system default if that variable is not set.
DESCRIPTION
The date command displays the date and, with superuser authority, sets the system date. The date command has been enhanced to support set-
ting the system date past the year 1999, thus providing customers with the ability to begin testing their software for potential century
rollover problems.
Displaying the Date
The date command writes the current date and time to standard output if called with no options or with a option list that begins with a +
(plus sign).
If you follow date with a + (plus sign) and a field descriptor, you can control the output of the command. You must precede each field
descriptor with a % (percent sign). The system replaces the field descriptor with the specified value. Enter a literal % as %%. The date
command copies any other characters to standard output without change. The date command always ends the string with a newline character.
Output fields are fixed size (zero padded if necessary).
[Tru64 UNIX] The date command prints out a usage message on any unrecognized options or input.
Field Descriptors
Displays the locale's abbreviated weekday name (Sun to Sat or the non-English equivalent). Displays the locale's full weekday name. Dis-
plays the locale's abbreviated month name. Displays the locale's full month name. Displays the locale's appropriate time and date repre-
sentation. Displays the locale's century (the year divided by 100 and truncated to an integer) as a decimal number (00 to 99). Displays
the day of month as a decimal number (01 to 31). Displays the date in the format mm/dd/yy independent of the value specified by the
LC_TIME environment variable, if defined. Displays the day of the month as a decimal number (1 to 31 in a 2-digit field with leading space
fill). Specifies the locale's alternative date and time representation. Specifies the name of the base year (period) in the locale's
alternative representation. Specifies the locale's alternative date representation. Specifies the locale's alternative time representa-
tion. Specifies the offset from %EC (year only) in the locale's alternative representation. Specifies the full alternative year represen-
tation. A synonym for %b. Displays the hour as a decimal number (00 to 23). Displays the hour as a decimal number (01 to 12). Displays
the day of year as a decimal number (001 to 366). Displays the month of year as a decimal number (01 to 12). Displays the minute as a
decimal number (00 to 59). Inserts a newline character. [Tru64 UNIX] Represents the alternative era name. [Tru64 UNIX] Represents the
alternative era year. Specifies the day of the month using the locale's alternative numeric symbols. Specifies the day of the month using
the locale's alternative numeric symbols. Specifies the hour (24-hour clock) using the locale's alternative numeric symbols. Specifies
the hour (12-hour clock) using the locale's alternative numeric symbols. Specifies the month using the locale's alternative numeric sym-
bols. Specifies the minutes using the locale's alternative numeric symbols. Specifies the seconds using the locale's alternative numeric
symbols. Specifies the weekday as a number in the locale's alternative representation (Monday=1). Specifies the week number of the year
(Sunday as the first day of the week) using the locale's alternative numeric symbols. Specifies the weekday as a number in the locale's
alternative representation (Sunday = 0). Specifies the week number of the year (Monday as the first day of the week) using the locale's
alternative numeric symbols. Specifies the year (offset from %C) in alternative representation. Displays the locale's equivalent of
either AM or PM. Displays the time (12-hour clock) using AM/PM notation (or the non-English equivalent) in the format hh:mm:ss AM or
hh:mm:ss PM. Displays the second as a decimal number (00 to 61). Inserts a tab character. Displays the time in 24-hour clock format as
hh:mm:ss (the default), or as specified by the LC_TIME environment variable, if defined. Displays the weekday as a decimal number [1,7],
with 1 representing Monday. Displays the week number of the year (Sunday is the first day of the week) as a decimal number (00 to 53).
All days in a new year preceding the first Sunday are considered to be in week 0. Displays the week number of the year (Monday as the
first day of the week) as a decimal number (01 to 53). If the week containing January 1 has four or more days in the new year, then it is
considered week 1; otherwise, it is week 53 of the previous year, and the next week is week 1. Displays the day of the week as a decimal
number (Sunday = 0). Displays the week number of the year (Monday is the first day of the week) as a decimal number (00 to 53). All days
in a new year preceding the first Monday are considered to be in week 0. Displays the locale's appropriate date representation. Displays
the locale's appropriate time representation. Displays the last two numbers of the year as a decimal number (00 to 99). Displays the full
year as a decimal number. Displays the time zone name, or no characters if the time zone cannot be determined. Inserts a % character.
Setting the Date
Only a user operating with superuser authority can change the date and time.
The default input format for setting the date is mmddHHMM[[cc]yy][.ss] where: mm is the month number (01=January). dd is the number of the
day in the month. HH is the hour in the day (using a 24-hour clock). MM is the number of minutes. cc is the first two digits of the
year. yy is the last two digits of the year. If this field is omitted, the current year is used. ss is the number of seconds.
The LC_TIME variable, if defined, controls the ordering of the day (dd) and month (mm) numbers in these formats. The default order is the
month (mm) followed by the day (dd).
Each of the Compaq formats allows you to specify the century (first two digits of the year). This century field (cc) is optional to ensure
that input formats previously accepted by the date command are still supported.
Currently, theXCU5.0 format does not have a century field. This is consistent with current X/Open specifications regarding the date com-
mand. The century field will be added to this format in a future release of the operating system once this new field is officially sup-
ported in future revisions of X/Open's UNIX specification.
[Tru64 UNIX] Reset the date in single-user mode only. Changing the date in multiuser mode could cause the creation and modifications dates
for user files to be inconsistent.
[Tru64 UNIX] To change the year, the system disk must be updated with the new year information. To change the year, in single-user mode
enter the following command after you enter a date containing a new year: mount -u /
The mount -u / command writes the new year into the superblock on the system disk. The root file system is now mounted read/write.
Handling of Two-Digit Year Input
When the year is specified using two digits (as in the XCU5.0 format or when the [cc] field is omitted from the Compaq formats), the cen-
tury is determined in the following manner: if the specified two-digit year is between 69 and 99 inclusive, the 20th century is assumed
(that is, 19yy); otherwise, the 21st century is assumed (that is, 20yy).
This algorithm for determining the century is consistent with current drafts of forthcoming X/Open UNIX specifications regarding two-digit
year handling in various system interfaces and commands, including the date command. This algorithm is based on the standard UNIX epoch
(12:00:00 AM Jan 1, 1970 UTC), minus one year to account for different time zones. Internal UNIX time handling is based on the number of
seconds in this epoch.
Handling of Ambiguous Input
If the input string is ambiguous, that is, if the format cannot be conclusively determined from the data, the date command will issue a
warning to stderr and assume the mmddHHMM[[cc]yy][.ss] format. To avoid ambiguous input, use one of the three Compaq formats and specify
the [cc] field.
EXAMPLES
To display current date and time, enter: date
Depending on your current locale, the output might look like one of the following: Thu Apr 16 13:21:30 EDT 1998
jeu 16 avr 17:21:30 CUT 1998
tor 16 apr 17:21:30 CUT 1998
The first output line is for an American English locale, the second is for a French locale, and the third is for a Danish locale.
To set the date and time, enter: date 02171425.45
This sets the date and time to 14:25:45 (45 seconds after 2:25 p.m.) February 17 of the current year. To display the date and time
in a specified format, enter: date +"%r %d %h %y (%a)"
This displays the date (assume current year is 1993) shown in Example 2 as: 02:25:45 PM 17 Feb 99 (Fri)
Do not set the date in multi-user mode.
Year 2000 Examples
To set the date to 09:34:00 AM Jan 7, 2000: Using the mmddHHMM[[cc]yy][.ss] Compaq format: date 010709342000 date 0107093400.00 date
010709342000.00 Using the [[cc]yy]mmddHHMM[.ss] Compaq format: date 0001070934 date 200001070934 date 200001070934.00 Using the mmd-
dHHMM[.ss[[cc]yy]] Compaq format: date 01070934.0000 date 01070934.002000 Using the mmddHHMM[yy] format: date 0107093400 An example of
ambiguous input: XCU5.0 date 0101010000
This input could be recognized as one of the following formats:
mmddHHMM[[cc]yy][.ss] meaning 01:00:00 AM Jan 1, 2000
[[cc]yy]mmddHHMM[.ss] meaning 12:00:00 AM Jan 1, 2001
In this case, the date command will display a warning and assume the mmddHHMM[[cc]yy][.ss] format, setting the date to 01:00:00 AM
Jan 1, 2000.
ENVIRONMENT VARIABLES
The following environment variables affect the execution of date: Provides a default value for the internationalization variables that are
unset or null. If LANG is unset or null, the corresponding value from the default locale is used. If any of the internationalization vari-
ables contain an invalid setting, the utility behaves as if none of the variables had been defined. If set to a non-empty string value,
overrides the values of all the other internationalization variables. Determines the locale for the interpretation of sequences of bytes
of text data as characters (for example, single-byte as opposed to multibyte characters in arguments). Determines the locale for the for-
mat and contents of diagnostic messages written to standard error. Determines the format of the date and time strings written by date.
Determines the location of message catalogues for the processing of LC_MESSAGES. Determines the time zone in which the time and date are
written, unless the -u option is specified. If the TZ variable is not set and the -u option is not specified, a system default time zone
is used.
SEE ALSO
Functions: gettimeofday(2)
Routines: ctime(3), getclock(3), setclock(3)
Standards: standards(5)
Command and Shell User's Guide
date(1)