The touch(1) utility sets the modification and access
times of files to the current time of day. If the file does not
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(1) utility does not treat this as an error. No error
messages are displayed and the exit value is not affected.
-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 modification 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 YY value between 69 and 99 refers to
the twentieth century (CC is 19); a YY value between
00 and 68 refers to the 21st century (CC is 20).
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.