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date(1) 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 XPG4-UNIX - Sets the Date
date [mmddHHMM[yy]
Using the Century Field Provided by Digital - 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: XPG4, XPG4-UNIX
Refer to the standards(5) reference page for more information about indus-
try standards and associated tags.
DESCRIPTION
The date command displays the date and, with superuser authority, sets the
system date. The date command has been enhanced to support setting the sys-
tem 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 flags or with a flag 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).
[Digital] The date command prints out a usage message on any unrecognized
flags or input.
Field Descriptors
a Displays the locale's abbreviated weekday name (Sun to Sat or the non-
English equivalent).
A Displays the locale's full weekday name.
b Displays the locale's abbreviated month name.
B Displays the locale's full month name.
c Displays the locale's appropriate time and date representation.
C Displays the locale's century (the year divided by 100 and truncated to
an integer) as a decimal number (00 to 99).
d Displays the day of month as a decimal number (01 to 31).
D Displays the date in the format mm/dd/yy independent of the value
specified by the LC_TIME environment variable, if defined.
e Displays the day of the month as a decimal number (1 to 31 in a 2-digit
field with leading space fill).
Ec Specifies the locale's alternative date and time representation.
EC Specifies the name of the base year (period) in the locale's alterna-
tive representation.
Ex Specifies the locale's alternative date representation.
EX Specifies the locale's alternative time representation.
Ey Specifies the offset from %EC (year only) in the locale's alternative
representation.
EY Specifies the full alternative year representation.
h A synonym for %b.
H Displays the hour as a decimal number (00 to 23).
I Displays the hour as a decimal number (01 to 12).
j Displays the day of year as a decimal number (001 to 366).
m Displays the month of year as a decimal number (01 to 12).
M Displays the minute as a decimal number (00 to 59).
n Inserts a newline character.
N [Digital] Represents the alternative era name.
o [Digital] Represents the alternative era year.
Od Specifies the day of the month using the locale's alternative numeric
symbols.
Oe Specifies the day of the month using the locale's alternative numeric
symbols.
OH Specifies the hour (24-hour clock) using the locale's alternative
numeric symbols.
OI Specifies the hour (12-hour clock) using the locale's alternative
numeric symbols.
Om Specifies the month using the locale's alternative numeric symbols.
OM Specifies the minutes using the locale's alternative numeric symbols.
OS Specifies the seconds using the locale's alternative numeric symbols.
Ou Specifies the weekday as a number in the locale's alternative represen-
tation (Monday=1).
OU Specifies the week number of the year (Sunday as the first day of the
week) using the locale's alternative numeric symbols.
Ow Specifies the weekday as a number in the locale's alternative represen-
tation (Sunday = 0).
OW Specifies the week number of the year (Monday as the first day of the
week) using the locale's alternative numeric symbols.
Oy Specifies the year (offset from %C) in alternative representation.
p Displays the locale's equivalent of either AM or PM.
r 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.
S Displays the second as a decimal number (00 to 61).
t Inserts a tab character.
T 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.
u Displays the weekday as a decimal number [1,7], with 1 representing
Monday.
U 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.
V 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 or the previous year, and the next week is
week 1.
w Displays the day of the week as a decimal number (Sunday = 0).
W 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.
x Displays the locale's appropriate date representation.
X Displays the locale's appropriate time representation.
y Displays the last two numbers of the year as a decimal number (00 to
99).
Y Displays the full year as a decimal number.
Z 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.
Note that 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 Digital 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, the XPG4-UNIX format does not have a century field. This is
consistent with current X/Open specifications regarding the date command.
The century field will be added to this format in a future release of the
operating system once this new field is officially supported in future
revisions of X/Open's UNIX specification.
[Digital] 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.
[Digital] 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 com-
mand:
mount -u /
after you enter a date containing a new year. The mount -u / command writes
the new year into the superblock on the system disk. The root filesystem is
now mounted read/write.
Handling of Two-Digit Year Input
When the year is specified using two digits (as in the XPG4-UNIX format or
when the [cc] field is omitted from the Digital formats), the century 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 con-
clusively 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 Digital formats and specify the [cc] field.
FLAGS
-n [Digital] Does not set the time globally on all machines in a local
area network that have their clocks synchronized (superuser only).
-u 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.
ENVIRONMENT VARIABLES
The following environment variables affect the execution of date:
LANG Provides a default value for the internationalization variables
that are unset or null. If LANG is unset or null, the correspond-
ing value from the default locale is used. If any of the interna-
tionalization variables contain an invalid setting, the utility
behaves as if none of the variables had been defined.
LC_ALL If set to a non-empty string value, overrides the values of all
the other internationalization variables.
LC_CTYPE Determines the locale for the interpretation of sequences of bytes
of text data as characters (for example, single-byte as opposed to
multi-byte characters in arguments).
LC_MESSAGES
Determines the locale for the format and contents of diagnostic
messages written to standard error.
LC_TIME Determines the format of the date and time strings written by
date.
NLSPATH Determines the location of message catalogues for the processing
of LC_MESSAGES.
TZ Determines the timezone in which the time and date are written.
unless the -u flag is specified. If the TZ variable is not set
and the -u flag is not specified, a system default time zone is
used.
EXAMPLES
1. To display current date and time, enter:
date
Depending on your current locale, the output might look like one of
the following:
Thu Apr 12 13:21:30 EDT 1992
jeu 12 avr 17:21:30 CUT 1992
tor 12 apr 17:21:30 CUT 1992
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.
2. 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.
3. 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:
02:25:03 PM 17 Feb 93 (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:
1. Using the mmddHHMM[[cc]yy][.ss] Digital format:
date 010709342000
date 0107093400.00
date 010709342000.00
2. Using the [[cc]yy]mmddHHMM[.ss] Digital format:
date 0001070934
date 200001070934
date 200001070934.00
3. Using the mmddHHMM[.ss[[cc]yy]] Digital format:
date 01070934.0000
date 01070934.002000
4. Using the mmddHHMM[yy] XPG4-UNIX format:
date 0107093400
5. An example of ambiguous input:
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.
RELATED INFORMATION
Functions: gettimeofday(2), ctime(3), getclock(3), setclock(3)
Standards: standards(5)
Documents: Command and Shell User's Guide
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