touch(1) touch(1)
NAME
touch - update access and modification times of a file
SYNOPSIS
touch [-acm] {-r referencefile | -t time} [--] file ... Format 1
touch [-acm] [time] [--] file ... Format 2
DESCRIPTION
touch is used to set the access and modification times of files to the
current or specified date.
OPTIONS
Format 1: New synopsis for touch
No option specified:
touch sets the time of the last modification and the time of the
last access for the specified files to the current date. If a
file does not yet exist touch creates one. Specifying touch
without an option has the same effect as touch -am.
-a (a - access time) touch sets the time of the last access for the
specified files.
Neither -a nor -m specified: touch sets the time of the last
modification and the time of the last access.
-c touch does not create files that do not exist. No message is
output here; the exit status is not set to an error.
-m (m - modification time) touch sets the time of the last modifi-
cation for the specified files.
Neither -a nor -m specified: touch sets the time of the last
modification and the time of the last access.
-r referencefile
Modification and access time of the file referencefile are used
instead of the current date.
-r must not be combined with -t or the obsolete argument time.
-t time
The time specified here is used instead of the current date.
time is specified in the following format:
[[CC]YY]MMDDhhmm[.SS]
CC The first two digits of a year: 19 or 20
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touch(1) touch(1)
CC not specified:
If the two-digit year notation YY is in the range 70 to 99,
the 20th century is assumed; if it is in the range 00 to
37, the 21st century is assumed. All other entries are
rejected.
YY Two-digit year notation
Only the digits >69 and <38 may be entered. If the year
number specified is <38, this is beyond the year 2000.
YY not specified: The current year is assumed.
MM Two-digit month notation (01 through 12)
DD Two-digit day notation (01 through 31)
hh Two-digit hour notation (00 through 23)
mm Two-digit minute notation (00 through 59)
SS Two-digit second notation (00 through 61)
The values 60 and 61 are intended for leap seconds.
SS not specified: The value 0 seconds is assumed.
-t must not be combined with -r or the obsolete argument time.
-- End of the list of options. Must be specified if file begins
with -.
file Name of the input file. touch processes all types of files and
directories. Several filenames can be specified for each call.
Format 2: Old synopsis for touch
time not specified:
touch sets the access and modification times of the named files
to the specified or current date. If a file does not exist, it
is created. Calling touch without options is thus equivalent to
touch -am.
-a Updates only the access time of the named files to the specified
or current date.
If neither -a nor -m is specified: touch sets the access and
modification times of the named files to the specified or
current date.
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touch(1) touch(1)
-c Prevents touch from creating a file if the named file did not
previously exist. No corresponding message is issued.
-m Updates only the modification time of the named files to the
specified or current date.
If neither -a nor -m is specified: touch sets both the access
and modification times of the named files to the specified or
current date.
mmddhhmm[yy]
Date and time to which the access and/or modification times of
the specified files are to be set. The date/time argument
comprises eight to ten digits with the following significance:
month (mm); day (dd); hour (hh); minute (mm); year (yy).
yy not specified: touch assumes you mean the current year.
Note: Time notations in this format are obsolete. Filenames con-
sisting only of digits can cause problems, as touch may be
interpreted as a date notation. You should replace time with the
-t option.
-- End of the list of options. Must be specified if time was not
specified and file begins with -.
file Name of the input file. touch processes all types of files,
including directories. Several file names may be specified in
one call.
ERROR MESSAGES
date: bad conversion
You have specified an illegal date, e.g. 13010000.
LOCALE
The LCMESSAGES environment variable governs the language in which
message texts are displayed. If LCMESSAGES is undefined or is defined
as the null string, it defaults to the value of LANG. If LANG is like-
wise undefined or null, the system acts as if it were not internation-
alized.
TZ defines the time zone for the -t option.
The LCALL environment variable governs the entire locale. LCALL
takes precedence over all the other environment variables which affect
internationalization.
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touch(1) touch(1)
EXAMPLES
Example 1
Set the access and modification times of file to the current date. No
new file is to be created if this file does not exist.
$ touch -c file
The ls -l command can be used to display the time of the last modifi-
cation; ls -lu outputs the access time.
Example 2
Set the access time of file to 9 o'clock on 8/26:
$ touch -a -t 08260900 file
$ ls -lu file
-rw-r--r-- 1 bert ap343 736 Aug 26 09:00 file
SEE ALSO
date(1), ls(1), utime(2).
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