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touch - change file access and modification times

 

NAME

      touch - change file access and modification times
 

SYNOPSIS

      touch [-acfm] [-r file] [-t [[CC]YY]MMDDhhmm[.SS]] file ...
 

DESCRIPTION

      The touch utility sets the modification and access 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.
 
      -f      Attempt to force the update, even if the file permissions do not
              currently permit it.
 
      -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.
              The argument should be in 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 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 61.
 
              If the “CC” and “YY” letter pairs are not specified, the values
              default to the current year.  If the “SS” letter pair is not
              specified, the value defaults to 0.
 

DIAGNOSTICS

      The touch utility exits 0 on success, and >0 if an error occurs.
      utimes(2)
 

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 counter‐
      parts 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.
 

HISTORY

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

STANDARDS

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

Sections

Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.