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touch(1)                  BSD General Commands Manual                 touch(1)


NAME

     touch -- change file access and modification times


SYNOPSIS

     touch [-A [-][[hh]mm]SS] [-acfhm] [-r file] [-t [[CC]YY]MMDDhhmm[.SS]]
           file ...


DESCRIPTION

     The touch utility sets the modification and access times of files.  If
     any file does not exist, it is created with default permissions.

     By default, touch changes both modification and access times.  The -a and
     -m flags may be used to select the access time or the modification time
     individually.  Selecting both is equivalent to the default.  By default,
     the timestamps are set to the current time.  The -t flag explicitly spec-
     ifies a different time, and the -r flag specifies to set the times those
     of the specified file.  The -A flag adjusts the values by a specified
     amount.

     The following options are available:

     -A      Adjust the access and modification time stamps for the file by
             the specified value.  This flag is intended for use in modifying
             files with incorrectly set time stamps.

             The argument is of the form ``[-][[hh]mm]SS'' where each pair of
             letters represents the following:

                   -       Make the adjustment negative: the new time stamp is
                           set to be before the old one.
                   hh      The number of hours, from 00 to 99.
                   mm      The number of minutes, from 00 to 59.
                   SS      The number of seconds, from 00 to 59.

             The -A flag implies the -c flag: if any file specified does not
             exist, it will be silently ignored.

     -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.

     -f      Attempt to force the update, even if the file permissions do not
             currently permit it.

     -h      If the file is a symbolic link, change the times of the link
             itself rather than the file that the link points to.  Note that
             -h implies -c and thus will not create any new files.

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

     -t      Change the access and modification times to the specified time
             instead of the current time of day.  The argument is of the form
             ``[[CC]YY]MMDDhhmm[.SS]'' where each pair of letters 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.
                           Otherwise, a ``CC'' value of 20 is used.
                   MM      The month of the year, from 01 to 12.
                   DD      the day of the month, from 01 to 31.
                   hh      The hour of the day, from 00 to 23.
                   mm      The minute of the hour, from 00 to 59.
                   SS      The second of the minute, from 00 to 61.

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


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 -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 39 to 99, the year is set to 1939 to 1999, otherwise, the year
     is set in the 21st century.


SEE ALSO

     utimes(2)


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.

BSD                             April 28, 1995                             BSD

Mac OS X 10.7 - Generated Wed Aug 10 16:46:32 CDT 2011