touch(1)							     touch(1)



NAME
  touch - Updates file access and modification times

SYNOPSIS

  touch [-acfm] [-r reference_file | -t time] file ...

  The following older syntax is now maintained for backward compatibility,
  but may be withdrawn in future issues:

  touch

  touch [-acfm] [time] file ...

FLAGS

  -a  Changes only the access time.

  -c  Suppresses the creation of the file.

  -f  Attempts to force the touch in spite of read and write permissions on a
      file.  -f is actually a dummy flag; it is not used by the touch code,
      but is recognized by getopt().

  -m  Changes only the modification time.

  -r reference_file
      Uses the time of the file named by the pathname reference_file instead
      of the current time. You cannot use -r and -t together.

  -t time
      Uses the specified time instead of the current time.

      The time argument is a decimal number in the following form:
	   [[CC]YY]MMDDhhmm[.SS]
      The paired decimal numbers in the preceding syntax line represent the
      following:

      CC  The first two digits of the year (the century)

      YY  The second two digits of the year (00-99)

      MM  The month of the year (01-12)

      DD  The day of the month (01-31)

      hh  The hour of the day (00-23)

      mm  The minute of the hour (00-59)

      SS  The second of the minute (00-61)


  Both CC and YY are optional.	If neither is specified, the current year is
  assumed.  If YY is specified, but CC is not, CC is derived as follows:

       If YY is 69-99, CC is 19.

       If YY is 00-68, CC is 20.

  The resulting time is affected by the value of the TZ environment variable.
  If the resulting time value precedes the Epoch, touch exits immediately
  with an error status.	 The range of valid times past the Epoch extends to
  at least midnight 1 January 2000 UCT.

  The range for SS is 00-61 rather than 00-59 because of leap seconds.	If SS
  is 60 or 61, and the resulting time, as affected by the TZ environment
  variable, does not refer to a leap second, the resulting time is one or two
  seconds after a time where SS is 59.	If SS is not given a value, it is
  assumed to be 0 (zero).

DESCRIPTION

  The touch command updates the access and modification times of each file or
  directory named to the one specified on the command line or to the current
  time if you do not specify a time.  You can specify the time with -t or by
  the time of the reference file with the -r option.  If you do not specify a
  time, touch uses the current time.  If you specify a file that does not
  exist, touch creates a file with that name unless you request otherwise
  with the -c flag.

  If neither the -a or -m flags are specified, touch behaves as though both
  of these flags were specified.

  The LC_TIME environment variable, if defined, specifies the order of month
  and day in the date specification and of hour and minute in the time
  specification.  Otherwise, these orders default to MMdd and hhmm.  The for-
  mat for the time argument is MMddhhmm[yy].

  The obsolescent format for the time argument is MMddhhmm[yy].

EXAMPLES

   1.  To update the access and modification times of a file, enter:
	    touch  program.c


       This sets the last access and last modification times of program.c to
       the current date and time.  If program.c does not exist, touch creates
       an empty file with that name.

   2.  To avoid creating a new file, enter:
	    touch  -c  program.c


   3.  To update only the modification time, enter:
	    touch  -m  *.o


       This updates only the last modification times of the files in the
       current directory that end with .o.  The touch command is often used
       in this way to alter the results of the make command.

   4.  To explicitly set the access and modification times, enter:
	    touch  -c  02171425	 program.c


       This sets the access and modification dates to 14:25 (2:25 p.m.)
       February 17 of the current year.	 (This assumes that you are using the
       default format.)

   5.  To touch a file with a numeric filename, include its full pathname or
       precede it with ./, so that the filename is not mistaken for the time
       argument.  For example, to touch the file 123.abc, enter:
	    touch -c ./123.abc


EXIT VALUES

  The return code from touch is the number of files whose times could not be
  successfully modified (including files that did not exist and were not
  created). If no errors occur, the exit status is 0 (zero).

RELATED INFORMATION

  Commands:  date(1).

  Functions:  utime(2).

  Files:  locale(4).