unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (OSF1-V5.1-alpha)
Page:
Section:
Apropos / Subsearch:
optional field



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  but may be withdrawn in future issues: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	[-acfm]	[time] file...

STANDARDS

  Interfaces documented	on this	reference page conform to industry standards
  as follows:

  touch:  XCU5.0

  Refer	to the standards(5) reference page for more information	about indus-
  try standards	and associated tags.

OPTIONS

  -a  Changes only the access time.

  -c  Suppresses the creation of the file.

  -f  [Tru64 UNIX]  Attempts to	force the touch	in spite of read and write
      permissions on a file.  The -f option is actually	a dummy	option;	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 fol-
      lows:

      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	vari-
      able.  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).

  If neither the -a option nor the -m options are specified, touch behaves as
  if you have specified	both options.

OPERANDS

  file
      The file for which times should be modified, or which should be
      created. If the file is a	symbolic link, the link	will be	traversed and
      filename resolution will continue.

      In the obsolescent version, if both the -r and -t	options	are omitted,
      and if the first file parameter is an eight or ten digit decimal
      integer, it is interpreted as a time parameter.

      The format for the time parameter	in the obsolesent syntax is

      MMDDhhmm[YY]



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 option.

  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].


NOTES

  The obsolescent version may be withdrawn from	future versions	of the XCU5.0
  standards.  The -r or	-t options should be used.


EXIT STATUS

  The following	exit values are	returned:

  0   Successful completion.

  >>0  [Tru64 UNIX]  The	number of files	whose times could not be successfully
      modified (including files	that did not exist and were not	created).

  When the -c option is	specified, files are suppressed	purposely, an error
  does not occur and a message is not written to standard error.  The exit
  status returns zero (0) for success.

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



ENVIRONMENT VARIABLES

  The following	environment variables affect the execution of touch:

  LANG
      Provides a default value for the internationalization variables that
      are unset	or null. If LANG is unset or null, the corresponding value
      from the default locale is used. If any of the internationalization
      variables	contain	an invalid setting, the	utility	behaves	as if none of
      the variables had	been defined.

  LC_ALL
      If set to	a non-empty string value, overrides the	values of all the
      other internationalization variables.

  LC_CTYPE
      Determines the locale for	the interpretation of sequences	of bytes of
      text data	as characters (for example, single-byte	as opposed to multi-
      byte characters in arguments).

  LC_MESSAGES
      Determines the locale for	the format and contents	of diagnostic mes-
      sages written to standard	error.

  LC_TIME
      [Tru64 UNIX]  This 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 format	for the	time argument is MMddhhmm[yy].

  NLSPATH
      Determines the location of message catalogues for	the processing of
      LC_MESSAGES.

  TZ  Determines the time zone to be used for interpreting the time specifi-
      cation.

SEE ALSO

  Commands:  date(1)

  Functions:  creat(2),	utime(2)

  Files:  locale(4)

  Standards:  standards(5)