On Unix-like operating systems, the touch command modifies file timestamps. If the file doesn’t exist, an empty file with that name is created.

This page covers the GNU/Linux version of touch.

Description

A timestamp is information associated with a file that identifies an important time in the file’s history. A file can have multiple timestamps, and some of them can be “forged” by setting them manually. Internally, the operating system stores these times as time elapsed since an arbitrary date called the epoch. For Unix like operating systems, the epoch is 00:00:00 UTC (Coordinated Universal Time), Thursday, 1 January 1970.

  • Description

  • Syntax

  • Options

  • Time zones

  • Exit status

  • Examples

  • Examples

  • Examples

  • Checking file times with stat

  • Related commands

  • Linux commands help

  • Time zones

  • Exit status

  • Examples

  • Examples

  • Checking file times with stat

In Linux, there are three timestamps associated with a file:

The atime and mtime are part of a file’s status metadata. Therefore, when you change the atime (-a) or mtime (-m) of a file, its ctime is automatically set to the current time.

There is no way to manually set the ctime.

A file’s atime or mtime can be set to the future or the past if the user owns the file.

Syntax

touch [[-a] [-m] | [–time=timetype] […]] [[-d datestring] | [-t timestamp]] [-c] [-f] [-h] [-r reffile] file [file …]

touch –version

touch –help

The only required argument to touch is a file name:

With no options, touch changes the atime, mtime, and ctime of file to the current system time.

Options

Notes

The -d option takes a human-readable date string. For example, “July 4”, “4 Jul”, “0:00”, or “Jul 4 2017 00:00:00”. If year, month, or day are omitted, the current system time values are used. If the time is omitted, midnight is used. The day may be specified before or after the month in the string. Single digit numbers may be prefixed with a zero, or not, according to preference. If seconds are specified, they are to be preceded in the time by a colon ( : ).

-t takes a numeric timestamp, which expresses the month, date, hour, and minute as MMDDHHMM. For example, 07040000 would be midnight on the fourth of July. Century, years, and seconds are optional, and may be specified as CCYYMMDDHHMM.SS. If seconds are specified, they are to be preceded with a period ( . ).

Specifying times in the future is okay. For example, -d “Jan 1 2029”. In addition to having write access, the user must also own a file to set its times to the past or future.

Because there is no way to manually set ctimes, the -r, -d, and -t options can modify only atimes and mtimes. When a file is touched, the ctime is always set to the current system time.

Time zones

If the value of environment variable TZ is set, all operations use that time zone. Otherwise, the system default time zone is used.

To set the TZ environment variable, use the command tzselect.

Exit status

The exit status of touch is zero if all operations were successful. Any nonzero value indicates failure.

Examples

touch file.txt

If file.txt exists, set its access, modification, and change times (atime, mtime, and ctime) to the current system time. If file.txt doesn’t exist, create an empty file with that name.

touch -c file.txt

If file.txt exists, set its times to the current system time. If it does not exist, do nothing.

touch -a file.txt

Change the atime of file.txt. The mtime is not changed. The ctime is set to the current system time. If file.txt does not exist, it is created.

touch -h mysym

Change the times of file mysym. If it’s a symbolic link, change the times of the symlink, not the times of the referenced file.

touch -cr a.txt b.txt

Change the access and modification times of b.txt to match the times of a.txt. The ctime will be set to the current system time. If file.txt does not exist, it is not created.

touch -ahmcr a.txt b.txt

Change the atime and mtime of b.txt to match the atime and mtime of a.txt. If file1.txt doesn’t exist, do nothing. If b.txt is a symlink, set the times of the symlink. Do not touch the referenced file.

touch –time=atime –no-dereference –time=mtime –no-create –reference=a.txt b.txt

Same as the previous command.

touch -d “October 31” - > boo.txt

Set the atime and mtime of standard output to midnight, October 31 of the current year. Redirect (>) standard output to boo.txt.

touch cannot overwrite the contents of an existing file, but the redirect will. If boot.txt does not exist, it is created. If boot.txt exists, it will be overwritten.

touch -t “10310000” - > boo.txt

Examples

touch -d “1 Feb” file1.txt

Set the atime and mtime of file1.txt to February 1st of the current year. The ctime is set to the current system time.

touch -d “February 1” file1.txt

touch –date=“1 February” file1.txt

touch -d “01:02” file1.txt

Set the atime and mtime of file1.txt to 1:02 AM, today.

touch -d “1:2” file1.txt

touch -md “Sep 1 1927 23:58:59” file1.txt

Set the mtime of file1.txt to September 1, 1927, 11:58 PM and 59 seconds. The ctime is set to the current system time. The atime is not changed.

touch –time=01020304 file1.txt

Set the atime and mtime of file1.txt to January 2, 3:04 AM of the current year. The ctime is set to the current system time.

touch -t 01020304 file1.txt

touch -t 5006070405 file1.txt

Set the atime and mtime of file1.txt to June 7, 2050, 4:05 AM. The ctime is set to the current system time.

touch -t 205007080405 file1.txt

Same as the previous command, but explicitly specifying the century (20).

touch -at 195003040506.59 file1.txt

Set the atime of file1.txt to March 4, 1950, 5:06 AM and 59 seconds. The ctime is set to the current system time. The mtime is not changed.

Checking file times with stat

You can check the times of a file using the stat command:

stat file.txt

stat: cannot stat ‘file.txt’: No such file or directory

touch file.txt; stat file.txt

File: ‘file.txt’ Size: 0 Blocks: 0 IO Block: 4096 regular empty file Device: 802h/2050d Inode: 668116 Links: 1 Access: (0664/-rw-rw-r–) Uid: ( 1001/ hope) Gid: ( 1002/ hope) Access: 2017-10-25 21:35:17.368254343 -0400 Modify: 2017-10-25 21:35:17.368254343 -0400 Change: 2017-10-25 21:35:17.368254343 -0400 Birth: -

touch -ad “July 12 1895” file.txt; stat file.txt

File: ‘file.txt’ Size: 0 Blocks: 0 IO Block: 4096 regular empty file Device: 802h/2050d Inode: 668116 Links: 1 Access: (0664/-rw-rw-r–) Uid: ( 1001/ hope) Gid: ( 1002/ hope) Access: 1895-07-12 00:00:00.000000000 -0500 Modify: 2017-10-25 21:35:17.368254343 -0400 Change: 2017-10-25 21:35:55.487636366 -0400 Birth: -

touch -mt 198307010000 file.txt; stat file.txt

File: ‘file.txt’ Size: 0 Blocks: 0 IO Block: 4096 regular empty file Device: 802h/2050d Inode: 668116 Links: 1 Access: (0664/-rw-rw-r–) Uid: ( 1001/ hope) Gid: ( 1002/ hope) Access: 1895-07-12 00:00:00.000000000 -0500 Modify: 1983-07-01 00:00:00.000000000 -0400 Change: 2017-10-25 21:36:59.654589018 -0400 Birth: -

for formatspec in ‘file name:\t%n’ ‘accessed:\t%x’ ‘modified:\t%y’ ‘changed:\t%z’; do stat –printf="$formatspec\n" file.txt; done

file name: file.txt accessed: 1895-07-12 00:00:00.000000000 -0500 modified: 1983-07-01 00:00:00.000000000 -0400 changed: 2017-10-25 21:36:59.654589018 -0400

date — View or set the current date and time.stat — Display the status of a file or filesystem.

You may notice in this set of examples that when the atime was changed to July 12, 1895, the time zone changed. That’s because DST (Daylight Savings Time) was not enacted in North America until April 1, 1918.