touch - create a file or change its timestamps
$ touch [-acm] [-r ref_file|-t time|-d date_time] <path...>touch updates the last access and last modification times of all files specified in path to the current time.
Unless -c is specified, touch creates a regular empty file for a path that does not exist.
-a: Change access time of file-c: Do not create a file if it does not exist-m: Change modification time of file-r: Use time of file specified by reference path instead of current time-t: Use specified time in format [[CC]YY]MMDDhhmm[.SS] instead of current time-d: Use specified datetime in formats YYYY-MM-DDThh:mm:SS[.frac][tz] or YYYY-MM-DDThh:mm:SS[,frac][tz] instead of current time# Create or update a file named 'file' with its last access and last
# modification attributes set to the current time:
$ touch file
# Update a file called 'somefile' with last access and last modification
# timestamps set to 14:49:30 on May 13, 2009:
$ touch -c -d '2009-05-13 14:49:30' somefile
# Create or update a file called 'anotherfile', where the resulting file has
# both last modification and last access timestamps set to April 4, 1971 at
# 09:17:00 local time:
$ touch -t 197104180917 anotherfile
# Create or update a file called 'thatfile'. It's last access time is set to
# the last access time of the file named 'anotherfile' instead of the current
# time, and the last modification time remains unchanged as long as the file
# exists:
$ touch -r anotherfile thatfilemktemp(1) to create a temporary filefutimens(2)utimensat(2)