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

Official packages exist for:

Community maintained packages:

Documentation

A lot of work has been put into making documentation for GNU parallel.

Citation

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

Mailing lists

GNU parallel has two mailing lists: <[email protected]> and <[email protected]>

The main discussion list is <[email protected]>, and is used to discuss uses of GNU parallel. Subscribe at http://lists.gnu.org/mailman/listinfo/parallel.

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

Subscribe at http://lists.gnu.org/mailman/listinfo/bug-parallel.

Announcements about GNU parallel and most other GNU software are made on <[email protected]>. Subscribe at http://lists.gnu.org/mailman/listinfo/info-gnu.

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 http://alpha.gnu.org/gnu/parallel/ (via HTTP) and ftp://alpha.gnu.org/gnu/parallel/ (via FTP).
Development
For development sources, bug and patch trackers, and other information, please see the GNU parallel project page at savannah.gnu.org.
Maintainer
GNU parallel is currently being maintained by Ole Tange (http://ole.tange.dk). Please use the mailing lists for contact.

Merchandise

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

Licensing

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 (2018): GNU Parallel 2018, March 2018, https://doi.org/10.5281/zenodo.1146014.

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