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GNU Parallel

GNU Parallel
For people who live life in the parallel lane.
GNU parallel is a shell tool for executing jobs in parallel using one or more computers. A job can be a single command or a small script that has to be run for each of the lines in the input. The typical input is a list of files, a list of hosts, a list of users, a list of URLs, or a list of tables. A job can also be a command that reads from a pipe. GNU parallel can then split the input and pipe it into commands in parallel.

If you use xargs and tee today you will find GNU parallel very easy to use as GNU parallel is written to have the same options as xargs. If you write loops in shell, you will find GNU parallel may be able to replace most of the loops and make them run faster by running several jobs in parallel.

GNU parallel makes sure output from the commands is the same output as you would get had you run the commands sequentially. This makes it possible to use output from GNU parallel as input for other programs.

For each line of input GNU parallel will execute command with the line as arguments. If no command is given, the line of input is executed. Several lines will be run in parallel. GNU parallel can often be used as a substitute for xargs or cat | bash.

Downloading GNU Parallel

GNU parallel can be found on the main GNU ftp server: (via HTTP) and (via FTP). It can also be found on the GNU mirrors; please use a mirror if possible.

Official packages exist for:

Community maintained packages:


Just like other GNU software GNU parallel has documentation available online:

  • You can get a description of the design decisions behind GNU parallel by running man parallel_design.
  • You may also find more information about GNU parallel by looking at /usr/doc/parallel/, /usr/local/doc/parallel/, or similar directories on your system.

    Some short videos displaying the most common usage are available at:

    The history of GNU parallel can be found at

    The package includes GNU sem, GNU sql, and GNU niceload.


    When using GNU parallel for a publication please cite as per parallel --bibtex.

    Mailing lists

    GNU parallel has two mailing lists: <> and <>

    The main discussion list is <>, and is used to discuss uses of GNU parallel. Subscribe at

    The discussion list <>, is used to discuss development and enhancement requests, as well as bug reports. Your bug report should always include:

    Subscribe at

    Announcements about GNU parallel and most other GNU software are made on <>. Subscribe at

    Getting involved

    Development of GNU parallel, and GNU in general, is a volunteer effort, and you can contribute. For information, please read How to help GNU. If you'd like to get involved, it's a good idea to join the discussion mailing list (see above).

    Test releases
    Trying the latest test release (when available) is always appreciated. Test releases of GNU parallel can be found at (via HTTP) and (via FTP).
    For development sources, bug and patch trackers, and other information, please see the GNU parallel project page at
    GNU parallel is currently being maintained by Ole Tange ( Please use the mailing lists for contact.


    You can show your support for GNU parallel using our merchandise.


    GNU parallel is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

    When using GNU parallel for a publication please cite:

    O. Tange (2011): GNU Parallel - The Command-Line Power Tool, ;login: The USENIX Magazine, February 2011:42-47.

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    The Free Software Foundation is the principal organizational sponsor of the GNU Operating System. Support GNU and the FSF by buying manuals and gear, joining the FSF as an associate member, or making a donation, either directly to the FSF or via Flattr.

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