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 touch(1)							    touch(1)




 NAME
      touch - update access, modification, and/or change times of file

 SYNOPSIS
      touch [-amc] [-r ref_file | -t time] file_name ...

    Obsolescent:
      touch time_str file_name ...

 DESCRIPTION
      touch updates the access, modification, and last-change times of each
      argument.	 The file name is created if it does not exist.	 If no time
      is specified (see date(1)) the current time is used.

      The -r and -t options are mutually exclusive.

    Options
      The following options are available:

	   -a	     Change the access time of file_name to time, or to the
		     current time if time is not specified.  Do not change
		     the modification time unless -m is also specified.

	   -m	     Change the modification time of file_name to time, or
		     to the current time if time is not specified.  Do not
		     change the access time unless -a is also specified.

	   -c	     Silently prevent touch from creating the file if it did
		     not previously exist.  Do not write any diagnostic
		     messages concerning this condition.

	   -r ref_file
		     Use the corresponding time of ref_file instead of the
		     current time.

	   -t time   Use the specified time instead of the current time.
		     The option argument is a decimal number of the form:

			  [[CC]YY]MMDDhhmm[.SS]

		     where each two digits represents the following:

			  CC	  The first two digits of the year.

			  YY	  The second two digits of the year.

			  MM	  The month of the year (01-12).

			  DD	  The day of the month (01-31).





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 touch(1)							    touch(1)




			  hh	  The hour of the day (00-23).

			  mm	  The minute of the hour (00-59).

			  SS	  The second of the minute (00-61).

		     If neither CC nor YY is given, the current year is
		     assumed.  If YY is specified, but CC is not, CC is
		     derived as follows: (taken into account the local time
		     factor)
			  If YY is:   CC becomes:
			  _______________________
			    69-99	  19
			    00-68	  20

		     If the resulting time value precedes the Epoch
		     (00:00:00 January 1, 1970 Greenwich Mean Time), touch
		     exits immediately with an error status.

		     The range for SS is 00 through 61 rather than 00
		     through 59 to accommodate 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 second after a time where SS
		     is 59.  If SS is not given a value, it is assumed to be
		     0.

      The syntax shown by the second SYNOPSIS line is recognized when
      neither the -r option, the -t option, nor the -- option delimiter is
      specified, and the first operand consists of all decimal digits.	This
      operand is interpreted as the time argument instead of as a file name.
      However, in this case, time_str is assumed to be of the form:

	   MMDDhhmm[YY]

      This is for backward compatibility.  The -t form given above is
      recommended for future portability.  The -- option delimiter can be
      used before the first file_name if there is a possibility that
      file_name consists of all digits, in order to ensure that the first
      syntax is used.

      touch succeeds only when invoked by the owner of the file if any of
      the following are true:

	   +  A time is specified,

	   +  Only the access time of the file is being updated, or

	   +  Only the modification time of the file is being updated.





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 touch(1)							    touch(1)




      In addition, touch succeeds when invoked by a user with write
      permission on the file if both of the following are true:

	   +  No time is specified, and

	   +  Both the access time and modification time of the file are
	      being updated.

 EXTERNAL INFLUENCES
    Environment Variables
      TZ   If the time is specified via the -t option, TZ is used to
	   interpret the time for the specified time zone.

      LC_MESSAGES determines the language in which messages are displayed.

      If LC_MESSAGES is not specified in the environment or is set to the
      empty string, the value of LANG is used as a default for each
      unspecified or empty variable.  If LANG is not specified or is set to
      the empty string, a default of "C" (see lang(5)) is used instead of
      LANG.

      If any internationalization variable contains an invalid setting,
      touch behaves as if all internationalization variables are set to "C".
      See environ(5).

    International Code Set Support
      Single- and multi-byte character code sets are supported.

 RETURN VALUE
      touch returns zero if all file_name arguments were successfully
      changed.

      touch returns non-zero and prints out a diagnostic message if an
      invalid time or a time earlier than the Epoch was specified with the
      -t option, or if the -r and -t options were both specified, or if one
      or more of the file_name arguments could not be accessed.

 EXAMPLES
      The following command sets the modification and access times of the
      file named "bastille" to midnight, July 14, 1989, creating the file if
      it does not already exist.

	   touch -t 8907140000 bastille

      The following command does the same thing using the backward-
      compatible syntax:

	   touch 0714000089 bastille

      The following command sets the time of the two files named
      "0714000089" and "bastille" to the current time, creating them if they



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 touch(1)							    touch(1)




      do not exist:

	   touch -- 0714000089 bastille

      To create a zero-length file, use any of the following:

	   touch file
	   cat /dev/null >&gt&gt>file
	   cp /dev/null file

 DEPENDENCIES
    NFS:
      An attempt to touch a file owned by the super-user on a remote server
      might fail, even if the invoking user has write permission on the
      file.

 SEE ALSO
      date(1), utime(2).

 STANDARDS CONFORMANCE
      touch: SVID2, SVID3, XPG2, XPG3, XPG4, POSIX.2

































 Hewlett-Packard Company	    - 4 -   HP-UX Release 11i: November 2000