touch - change file timestamps


     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]  [--]


     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


     -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
          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 speci-
          fied  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.


     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


     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, timezones, `am' and `pm', etc.

     -f   Ignored;  for  compatibility  with  BSD   versions   of

     -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


          Print a usage message on standard output and exit  suc-

          Print version information on standard output, then exit

     --   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 implementa-


     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-3.16
     package;  other  versions  may differ slightly. Mail correc-
     tions and additions to  and
     and .  Report bugs in the program