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Linux in a Nutshell

This directory of Linux commands is from Linux in a Nutshell, 5th Edition.

Click on any of the 687 commands below to get a description and list of available options. All links in the command summaries point to the online version of the book on Safari Bookshelf.

Buy it now, or read it online on Safari Bookshelf.


touch [options] files

For one or more files, update the access time and modification time (and dates) to the current time and date. touch is useful in forcing other commands to handle files a certain way; for example, the operation of make, and sometimes find, relies on a file's access and modification time. If a file doesn't exist, touch creates it with a file size of 0.


-a, --time=atime, --time=access, --time=use

Update only the access time.

-c, --no-create

Do not create any file that doesn't already exist.

-d time, --date time

Change the time value to the specified time instead of the current time. time can use several formats and may contain month names, time zones, a.m. and p.m. strings, etc.

-m, --time=mtime, --time=modify

Update only the modification time.

-r file, --reference file

Change times to be the same as those of the specified file, instead of the current time.

-t time

Use the time specified in time instead of the current time. This argument must be of the format [[cc] yy] mmddhhmm[.ss] , indicating optional century and year, month, date, hours, minutes, and optional seconds.


Print help message and then exit.


Print the version number and then exit.

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