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NAME

touch — change file access and modification times

SYNOPSIS

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 options are as follows:

-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.

-d ccyy-mm-ddTHH:MM:SS[.frac][Z]

Change the access and modification times to the specified time, in a format compliant with the ISO 8601 standard. The parts of the argument represent the following:

ccyy

Year.

mm

Month: a number from 1 to 12.

dd

Day: a number from 1 to 31.

T

Either the capital letter ‘T’ or a single space. If a space is used, the argument should be quoted to prevent the shell from splitting it into multiple words.

HH

Hour: a number from 0 to 23.

MM

Minute: a number from 0 to 59.

SS

Second: a number from 0 to 60 (permitting a leap second).

frac

The decimal fraction of the second, either a period or comma, followed by one or more decimal digits.

Z

The timezone specifier: a capital letter ‘Z’ indicating that the time is in UTC. If not specified, the time is in the local timezone.

-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 file

Use the access and modification times from the specified file instead of the current time of day.

-t [[cc]yy]mmddHHMM[.SS]

Change the access and modification times to the specified time, where the parts of the argument represent the following:

ccyy

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

Month: a number from 1 to 12.

dd

Day: a number from 1 to 31.

HH

Hour: a number from 0 to 23.

MM

Minute: a number from 0 to 59.

SS

Second: a number from 0 to 60 (permitting a leap second), preceded by a period. The default is 0.

EXIT STATUS

The touch utility exits 0 on success, and >0 if an error occurs.

SEE ALSO

date(1)

STANDARDS

The touch utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification.

The obsolescent form of touch, where a time format is specified as the first argument, is supported. When no -d, -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]”.

HISTORY

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