Originální popis anglicky:
touch - change file timestamps
Návod, kniha: General Commands Manual
touch [-acm][-r ref_file|-t time] [--]
file...
Obsolescent version:
touch [-acm][ugly_time] file...
GNU version:
touch [-acfm] [-r file] [-t decimtime]
[-d time] [--time={atime,access,use,mtime,modify}]
[--date=time] [--reference=file]
[--no-create] [--help] [--version] [--] file...
touch changes the access and/or modification timestamps of each specified
file. These timestamps are changed to the current time, unless the -r
option is specified, in which case they are changed to the corresponding
timestamps of the file
ref_file, or the -t option is specified, in
which case they are changed to the specified
time. Both times are
changed when neither or both of the -a and -m options are given. Only the
access or only the modification time is changed when one of the options -a and
-m is given. If the file did not exist yet, it is created (as an empty file
with mode 0666, modified by the umask), unless the -c option is given.
- -a
- Change the access time of file.
- -c
- Do not create file.
- -m
- Change the modification time of file.
- -r ref_file
- Use the corresponding timestamp of ref_file as the
new value for the changed timestamp(s).
- -t time
- Use the specified time as the new value for the changed
timestamp(s). The argument is a decimal number of the form
[[CC]YY]MMDDhhmm[.SS]
with the obvious meaning. If CC is not specified, the year CCYY is taken to
be in the range 1969-2068. If SS is not specified, it is taken to be 0. It
may be specified in the range 0-61 so that it is possible to refer to leap
seconds. The resulting time is taken as a time for the time zone specified
by the environment variable TZ. It is an error if the resulting time
precedes 1 January 1970.
- --
- Terminate option list.
The second form of invocation has the disadvantage that there is some ambiguity
as to whether
ugly_time is a time or a file argument. It is taken to be
a time when no -r or -t option is present, there are at least two arguments,
and the first argument is an eight- or ten-digit decimal integer. The format
of
ugly_time is MMDDhhmm[yy], where an yy in the range 69-99 denotes a
year in the range 1969-1999, and an unspecified yy denotes the current year.
This form is obsolete.
If the first
file would be a valid argument to the
-t option and
no timestamp is given with any of the
-d,
-r or
-t
options and the `--' argument is not given, that argument is interpreted as
the time for the other files instead of as a file name.
If changing both the access and modification times to the current time,
touch can change the timestamps for files that the user running it does
not own but has write permission for. Otherwise, the user must own the files.
- -a, --time=atime, --time=access, --time=use
- Change the access time only.
- -c, --no-create
- Do not create files that do not exist.
- -d, --date=time
- Use time instead of the current time. It can contain
month names, time zones, `am' and `pm', etc.
- -f
- Ignored; for compatibility with BSD versions of
touch(1).
- -m, --time=mtime, --time=modify
- Change the modification time only.
- -r file, --reference=file
- Use the times of the reference file instead of the
current time.
- -t decimtime
- Here decimtime has the format MMDDhhmm[[CC]YY][.ss]
Use the argument (months, days, hours, minutes, optional century and
years, optional seconds) instead of the current time. Note that this
format violates the POSIX specification.
- --help
- Print a usage message on standard output and exit
successfully.
- --version
- Print version information on standard output, then exit
successfully.
- --
- Terminate option list.
The variable TZ is used to interpret explicitly given times. The variables LANG,
LC_ALL, LC_CTYPE and LC_MESSAGES have the usual meaning.
POSIX 1003.2 describes a syntax for the argument of the -t option that differs
from that used by the GNU implementation.
The command `
touch foo' will create the file
foo if it didn't
exist, and change the time of last modification to now. It is often used to
guide the actions of
make.
This page describes
touch as found in the fileutils-4.0 package; other
versions may differ slightly.
