change file modification date 



touch [-acm] [-f agefile] [-r agefile] [[-t] time] file ...

touch [-acm] time file ...


The touch command changes certain dates for each file argument. By default, touch sets both the date of last file modification and the date of last file access to the current time. This is useful for maintaining correct release times for software and is particularly useful in conjunction with the MKS Make software development facility.



sets only the access time.


does not create any files that do not already exist. Normally, touch creates such files.


sets only the modification time.

If you do not specify -a or -m, touch behaves as though you specified both.

To tell touch to use a time other than the current, use one of the following options:

-f agefile 

is an obsolete version of the POSIX-compliant -r option.

-r agefile 

sets the access and modification times (as indicated by the other options) to those kept for agefile.

-t time 

specifies a particular time using this format:


where cc is the optional first 2 digits of the year, yy is the optional last 2 digits of the year, MM is the optional number of the month (01-12), dd is the optional day of the month, hh is the hour in 24 hour format (required), mm is the minutes (required), ss is the optional seconds.

An obsolete (but still supported) version of this command lets you omit the -t, but the format is:



touch newfile

sets the modification time of newfile to the present.

touch -t 8001031305 oldfile

sets the modification time of oldfile to 13:05 on January 3, 1980.

touch -r oldfile newfile

sets the modification time of newfile to that of oldfile.



contains the time zone that touch is to use when interpreting times.


Possible exit status values are:


Successful completion.


Failure due to any of the following:

— inability to access the desired file
— system cannot support such an early date
— inability to create a file
— inability to change a file's times

Failure that resulted in a usage message, including:

— unknown command line option
— only one of -t, -f, or -r is allowed
-r was missing the agefile
-t was missing its argument
— invalid date string (bad date conversion)


Age file inaccessible 

indicates that time could not be found for the file given with the -f or -r option either because that file does not exist or because the requesting user is not granted the appropriate permission for the file.

Missing age file argument 

You specified -f or -r, but did not give a file name after it.

Years earlier than year invalid 

Your system only recognizes dates back to the given year. touch does not accept dates before that time.

Bad date conversion 
Only one -r(-f) or -t flag allowed 
Missing date/time argument 



POSIX.2. x/OPEN Portability Guide 4.0. All UNIX systems. Windows 8.1. Windows Server 2012 R2. Windows 10. Windows Server 2016. Windows Server 2019. Windows 11. Windows Server 2022.


touch is provided as both an external utility and a built-in MKS KornShell utility.

On the extended FAT file system, the earliest date accepted is 1980. On the NTFS file system, the earliest date accepted is 1970.

The touch utility does not accept dates and times past 11:59.59 pm on December 31, 2099.


PTC MKS Toolkit for Power Users
PTC MKS Toolkit for System Administrators
PTC MKS Toolkit for Developers
PTC MKS Toolkit for Interoperability
PTC MKS Toolkit for Professional Developers
PTC MKS Toolkit for Professional Developers 64-Bit Edition
PTC MKS Toolkit for Enterprise Developers
PTC MKS Toolkit for Enterprise Developers 64-Bit Edition
PTC Windchill Requirements and Validation


cp, date, sh

PTC MKS Toolkit 10.4 Documentation Build 39.