touch(1) - NetBSD Manual Pages

TOUCH(1)                NetBSD General Commands Manual                TOUCH(1)


NAME

     touch -- change file access and modification times


SYNOPSIS

     touch [-acfhm] [-d human-datetime] [--date human-datetime] [-r file]
           [--reference file] [-t datetime] file ...


DESCRIPTION

     The touch utility changes the access and modification times of files to
     the current time of day.  If the file doesn't exist, it is created with
     default permissions.

     The following options are available:

     -a                 Change the access time of the file.  The modification
                        time of the file is not changed unless the -m flag is
                        also specified.

     -c                 Do not create the file if it does not exist.  The
                        touch utility does not treat this as an error.  No
                        error messages are displayed and the exit value is not
                        affected.

     -d human-datetime

     --date human-datetime
                        Parse human-datetime using the human datetime parser
                        parsedate(3).

     -f                 This flag has no effect; it is accepted for compati-
                        bility reasons.

     -h                 If file is a symbolic link, access and/or modification
                        time of the link is changed.  This option implies -c.

     -m                 Change the modification time of the file.  The access
                        time of the file is not changed unless the -a flag is
                        also specified.

     -r file

     --reference file   Use the access and modifications times from file
                        instead of the current time of day.

     -t datetime        Change the access and modification times to the speci-
                        fied time.  The argument datetime should be in the
                        form ``[[CC]YY]MMDDhhmm[.SS]'' where each pair of let-
                        ters represents the following:

                              CC      The first two digits of the year (the
                                      century).
                              YY      The second two digits of the year.  If
                                      ``YY'' is specified, but ``CC'' is not,
                                      a value for ``YY'' between 69 and 99
                                      results in a ``CC'' value of 19.  Other-
                                      wise, a ``CC'' value of 20 is used.
                              MM      The month of the year, from 1 to 12.
                              DD      The day of the month, from 1 to 31.
                              hh      The hour of the day, from 0 to 23.
                              mm      The minute of the hour, from 0 to 59.
                              SS      The second of the minute, from 0 to 60
                                      (permitting leap seconds).  If SS is 60
                                      and the resulting time, as affected by
                                      the TZ environment variable, does not
                                      refer to a leap second, the resulting
                                      time is one second after a time where SS
                                      is 59.  If SS is not given a value, it
                                      is assumed to be zero.

                        If the ``CC'' and ``YY'' letter pairs are not speci-
                        fied, the values default to the current year.  If the
                        ``SS'' letter pair is not specified, the value
                        defaults to 0.

     The -d, -r, and -t options are mutually exclusive.  If more than one of
     these options is present, the last one is used.


ENVIRONMENT

     TZ    The timezone to be used for interpreting the datetime argument of
           the -t option.


EXIT STATUS

     The touch utility exits 0 on success, and >0 if an error occurs.


COMPATIBILITY

     The obsolescent form of touch, where a time format is specified as the
     first argument, is supported.  When no -d, -r, or -t option is specified,
     there are at least two arguments, and the first argument is a string of
     digits either eight or ten characters in length, the first argument is
     interpreted as a time specification of the form ``MMDDhhmm[YY]''.

     The ``MM'', ``DD'', ``hh'' and ``mm'' letter pairs are treated as their
     counterparts specified to the -t option.  If the ``YY'' letter pair is in
     the range 69 to 99, the year is set to 1969 to 1999, otherwise, the year
     is set in the 21st century.


SEE ALSO

     utimes(2), parsedate(3)


STANDARDS

     The touch utility is expected to be a superset of the IEEE Std 1003.2
     (``POSIX.2'') specification.


HISTORY

     A touch utility appeared in Version 7 AT&T UNIX.


BUGS

     A symbolic link can't be a reference file of access and/or modification
     time.

NetBSD 10.99                   December 24, 2016                  NetBSD 10.99