GNU Parallel https://www.gnu.org/software/parallel/ = Presentation of GNU Parallel = 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. See the cheat sheet for examples that cover most of the daily usage: www.gnu.org/s/parallel/parallel_cheat.pdf = 10 seconds installation = For security reasons it is recommended you use your package manager to install. But if you cannot do that then you can use this 10 seconds installation. The 10 seconds installation will try to do a full installation; if that fails, a personal installation; if that fails, a minimal installation. $ (wget -O - pi.dk/3 || lynx -source pi.dk/3 || curl pi.dk/3/ || \ fetch -o - http://pi.dk/3 ) > install.sh $ sha1sum install.sh | grep 67bd7bc7dc20aff99eb8f1266574dadb 12345678 67bd7bc7 dc20aff9 9eb8f126 6574dadb $ md5sum install.sh | grep b7a15cdbb07fb6e11b0338577bc1780f b7a15cdb b07fb6e1 1b033857 7bc1780f $ sha512sum install.sh | grep 186000b62b66969d7506ca4f885e0c80e02a22444 6f25960b d4b90cf6 ba5b76de c1acdf39 f3d24249 72930394 a4164351 93a7668d 21ff9839 6f920be5 186000b6 2b66969d 7506ca4f 885e0c80 e02a2244 40e8a43f $ bash install.sh This will literally install faster than reading the rest of this document. = Full installation = Full installation of GNU Parallel is as simple as: wget https://ftpmirror.gnu.org/parallel/parallel-20201122.tar.bz2 wget https://ftpmirror.gnu.org/parallel/parallel-20201122.tar.bz2.sig gpg parallel-20201122.tar.bz2.sig bzip2 -dc parallel-20201122.tar.bz2 | tar xvf - cd parallel-20201122 ./configure && make && sudo make install = Personal installation = If you are not root you can add ~/bin to your path and install in ~/bin and ~/share: wget https://ftpmirror.gnu.org/parallel/parallel-20201122.tar.bz2 wget https://ftpmirror.gnu.org/parallel/parallel-20201122.tar.bz2.sig gpg parallel-20201122.tar.bz2.sig bzip2 -dc parallel-20201122.tar.bz2 | tar xvf - cd parallel-20201122 ./configure --prefix=$HOME && make && make install Or if your system lacks 'make' you can simply copy src/parallel src/sem src/niceload src/sql to a dir in your path. = Minimal installation = If you just need parallel and do not have 'make' installed (maybe the system is old or Microsoft Windows): wget https://git.savannah.gnu.org/cgit/parallel.git/plain/src/parallel chmod 755 parallel cp parallel sem mv parallel sem dir-in-your-$PATH/bin/ = Installation on compute servers = If you are developing your script to run on a remote server, that does not have GNU Parallel installed, but you have it installed on you development machine, the use can use `parallel --embed`. parallel --embed > newscript.sh Just edit the last lines of newscript.sh and copy it to the compute server. = Test the installation = After this you should be able to do: parallel -j0 ping -nc 3 ::: qubes-os.org gnu.org freenetproject.org This will send 3 ping packets to 3 different hosts in parallel and print the output when they complete. Watch the intro video for a quick introduction: https://www.youtube.com/playlist?list=PL284C9FF2488BC6D1 Walk through the tutorial (man parallel_tutorial). You command line will love you for it. When using programs that use GNU Parallel to process data for publication please cite: Tange, O. (2020, November 22). GNU Parallel 20201122 ('Biden'). Zenodo. https://doi.org/10.5281/zenodo.4284075 Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Ole Tange, http://ole.tange.dk and Free Software Foundation, Inc. = New versions = New versions will be released at: https://ftp.gnu.org/gnu/parallel/ = Dependencies = GNU Parallel should work with a normal full Perl installation. However, if you system has split up Perl into multiple packages then these are the important ones: opkg install perlbase-getopt perlbase-ipc procps-ng-ps perlbase-mime