ps

Last updated Aug 18, 2023

ps reports a list of the currently running processes.

Most versions accept unix, BSD and GNU style options.

On most MacOS and Linux installations the ps command is already available. It can however be installed using the distributions package manager.

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$ (apt-get install|apk add|yum install) procps

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$ ps
  PID TTY           TIME CMD
 2068 ttys001    0:00.64 /bin/zsh -l

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$ (ps -e | ps a)
  PID TTY           TIME CMD
 2068 ttys001    0:00.67 /bin/zsh -l
65418 ttys001    0:00.00 ps -e
13824 ttys002    0:00.12 /bin/zsh -l

You can print only specific columns if you wish to perform an action with the output like parsing with AWK or filtering with grep.

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$ ps -o pid,comm   
  PID COMM
 2068 /bin/zsh
13824 /bin/zsh

For example to count the number of instances of zsh running for the current user.

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$ ps -o comm | grep -c 'zsh'
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