touch(1) [netbsd man page]
TOUCH(1) BSD General Commands Manual TOUCH(1) NAME
touch -- change file access and modification times SYNOPSIS
touch [-acfhm] [-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 This flag has no effect; it is accepted for compatibility reasons. -h If file is a symbolic link, access and/or modification time of the link is changed. This option implies -c. -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. The touch utility exits 0 on success, and >0 if an error occurs. 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 counterparts specified to the -t option. If the ``YY'' letter pair is in the range 69 to 99, the year is set to 1969 to 1999, otherwise, the year is set in the 21st century. SEE ALSO
utimes(2) STANDARDS
The touch utility is expected to be a superset of the IEEE Std 1003.2 (``POSIX.2'') specification. HISTORY
A touch utility appeared in Version 7 AT&T UNIX. BUGS
A symbolic link can't be a reference file of access and/or modification time. BSD
February 22, 2011 BSD
Check Out this Related Man Page
touch(1) User Commands touch(1) NAME
touch, settime - change file access and modification times SYNOPSIS
touch [-acm] [-r ref_file | -t time] file... touch [-acm] [date_time] file... settime [-f ref_file] [date_time] file... DESCRIPTION
The touch utility sets the access and modification times of each file. The file operand is created if it does not already exist. The time used can be specified by -t time, by the corresponding time fields of the file referenced by -r ref_file, or by the date_time op- erand. If none of these are specified, touch uses the current time (the value returned by the time(2) function). If neither the -a nor -m options are specified, touch updates both the modification and access times. A user with write access to a file, but who is not the owner of the file or a super-user, can change the modification and access times of that file only to the current time. Attempts to set a specific time with touch will result in an error. The settime utility is equivalent to touch -c [date_time] file. OPTIONS
The following options are supported in the touch and settime utilities: touch The following options are supported for the touch utility: -a Changes the access time of file. Does not change the modification time unless -m is also specified. -c Does not create a specified file if it does not exist. Does not write any diagnostic messages concerning this condition. -m Changes the modification time of file. Does not change the access time unless -a is also specified. -r ref_file Uses the corresponding times of the file named by ref_file instead of the current time. -t time Uses the specified time instead of the current time. time will be a decimal number of the form: [[CC]YY]MMDDhhmm[.SS] where each two digits represent the following: 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]. CC The first two digits of the year. YY The second two digits of the year. SS The second of the minute [00-61]. Both CC and YY are optional. If neither is given, the current year will be assumed. If YY is specified, but CC is not, CC will be derived as follows: +-----------------------------------------------------------+ | If YY is: CC becomes: | +-----------------------------------------------------------+ |69-99 19 | |00-38 20 | |39-68 ERROR | +-----------------------------------------------------------+ The resulting time will be affected by the value of the TZ environment variable. If the resulting time value precedes the Epoch, touch will exit immediately with an error status. The range of valid times is the Epoch to January 18, 2038. 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 will be one or two seconds after a time where SS is 59. If SS is not given, it is assumed to be 0. settime The following option is supported for the settime utility: -f ref_file Uses the corresponding times of the file named by ref_file instead of the current time. OPERANDS
The following operands are supported for the touch and settime utilities: file A path name of a file whose times are to be modified. date_time Uses the specified date_time instead of the current time. This operand is a decimal number of the form: MMDDhhmm[YY] where each two digits represent the following: 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]. YY The second two digits of the year. YY is optional. If it is omitted, the current year will be assumed. If YY is specified, the year will be derived as follows: +-----------------------------------------------------------+ | YY Corresponding Year | |69-99 1969-1999 | |00-38 2000-2038 | |39-68 ERROR | +-----------------------------------------------------------+ If no -r option is specified, no -t option is specified, at least two operands are specified, and the first operand is an eight- or ten-digit decimal integer, the first operand will be assumed to be a date_time operand. Otherwise, the first operand will be assumed to be a file operand. USAGE
See largefile(5) for the description of the behavior of touch when encountering files greater than or equal to 2 Gbyte ( 2^31 bytes). When existing file access and modification times cannot be determined (which will occur if a call to stat(2) fails), both times can be changed to known values by settime and utime(2). However, in this case, touch -a (without -m) and touch -m (without -a) will fail because the unchanged time cannot be preserved. ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables that affect the execution of touch: LANG, LC_ALL, LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH. TZ Determine the timezone to be used for interpreting the time option-argument or the date_time operand. EXIT STATUS
The following exit values are returned: 0 The touch utility executed successfully and all requested changes were made. >0 An error occurred. The touch utility returned the number of files for which the times could not be successfully modified. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ |CSI |Enabled | +-----------------------------+-----------------------------+ |Interface Stability |Committed | +-----------------------------+-----------------------------+ |Standard |See standards(5). | +-----------------------------+-----------------------------+ SEE ALSO
stat(2), time(2), utime(2), attributes(5), environ(5), largefile(5), standards(5) NOTES
Users familiar with the BSD environment will find that for the touch utility, the -f option is accepted but ignored. The -f option is unnecessary because touch will succeed for all files owned by the user regardless of the permissions on the files. SunOS 5.11 9 Sep 2008 touch(1)