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parallel — Run commands on multiple CPU cores. See also: `xargs`. More information: <https://www.gnu.org/softwa

Submitted by: @import:tldr-pages··
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Problem

How to use the parallel command: Run commands on multiple CPU cores. See also: xargs. More information: <https://www.gnu.org/software/parallel/man.html>.

Solution

parallel — Run commands on multiple CPU cores. See also: xargs. More information: <https://www.gnu.org/software/parallel/man.html>.

Gzip several files at once, using all cores:
parallel gzip ::: {{path/to/file1 path/to/file2 ...}}


Read arguments from stdin, run 4 jobs at once:
ls *.txt | parallel {{[-j|--jobs]}} 4 gzip


Convert JPEG images to PNG using replacement strings:
parallel convert {} {.}.png ::: *.jpg


Parallel xargs, cram as many args as possible onto one command:
{{args}} | parallel -X {{command}}


Break stdin into ~1M blocks, feed each block to stdin of new command:
cat {{big_file.txt}} | parallel --pipe --block 1M {{command}}


Run on multiple machines via SSH:
parallel {{[-S|--sshlogin]}} {{machine1}},{{machine2}} {{command}} ::: {{arg1}} {{arg2}}


Download 4 files simultaneously from a text file containing links showing progress:
parallel {{[-j|--jobs]}} 4 --bar --eta curl {{[-sO|--silent --remote-name]}} {} :::: {{path/to/links.txt}}


Print the jobs which parallel is running in stderr:
parallel {{[-t|--verbose]}} {{command}} ::: {{args}}

Code Snippets

Gzip several files at once, using all cores

parallel gzip ::: {{path/to/file1 path/to/file2 ...}}

Read arguments from `stdin`, run 4 jobs at once

ls *.txt | parallel {{[-j|--jobs]}} 4 gzip

Convert JPEG images to PNG using replacement strings

parallel convert {} {.}.png ::: *.jpg

Parallel xargs, cram as many args as possible onto one command

{{args}} | parallel -X {{command}}

Break `stdin` into ~1M blocks, feed each block to `stdin` of new command

cat {{big_file.txt}} | parallel --pipe --block 1M {{command}}

Context

tldr-pages: common/parallel

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