pkill and pgrep: Process Management Commands

This is a introduction to *nix’s process management tools: pkill and pgrep. As this site’s domain name was, a introduction to pkill should exist here.


pgrep, pkill – look up or signal processes based on name and other attributes


pgrep [-flvx] [-d delimiter] [-n|-o] [-P ppid,...] [-g pgrp,...]
[-s sid,...] [-u euid,...] [-U uid,...] [-G gid,...]
[-t term,...] [pattern]

pkill [-signal] [-fvx] [-n|-o] [-P ppid,...] [-g pgrp,...]
[-s sid,...] [-u euid,...] [-U uid,...] [-G gid,...]
[-t term,...] [pattern]


pgrep  looks through the currently running processes and lists the process IDs which matches the selection criteria to stdout.  All the criteria have to match.  For example,

pgrep -u root sshd

will only list the processes called sshd AND owned by root.  On the other hand,

pgrep -u root,daemon

will list the processes owned by root OR daemon.

pkill will send the specified signal (by default SIGTERM) to each process instead of listing them on stdout.


-d delimiter
Sets the string used to delimit each process ID in the output (by default a newline).  (pgrep only.)

-f The pattern is normally only matched against the process name.  When -f is set, the full command  line  is used.

-g pgrp,…
Only  match  processes  in  the  process  group IDs listed.  Process group 0 is translated into pgrep’s or pkill’s own process group.

-G gid,…
Only match processes whose real group ID is listed.  Either the numerical or symbolical value may be used.

-l List the process name as well as the process ID. (pgrep only.)

-n Select only the newest (most recently started) of the matching processes.

-o Select only the oldest (least recently started) of the matching processes.

-P ppid,…
Only match processes whose parent process ID is listed.

-s sid,…
Only  match  processes  whose  process  session  ID is listed.  Session ID 0 is translated into pgrep’s or pkill’s own session ID.

-t term,…
Only match processes whose controlling terminal is listed.  The terminal name should be specified  without the “/dev/” prefix.

-u euid,…
Only  match  processes whose effective user ID is listed.  Either the numerical or symbolical value may be used.

-U uid,…
Only match processes whose real user ID is listed.  Either the numerical or symbolical value may be  used.

-v Negates the matching.

-x Only match processes whose name (or command line if -f is specified) exactly match the pattern.

Defines the signal to send to each matched process.  Either the numeric or the symbolic signal name can be used.  (pkill only.)


Specifies an Extended Regular Expression for matching against the process names or command lines.


Example 1: Find the process ID of the named daemon:

unix$ pgrep -u root named

Example 2: Make syslog reread its configuration file:

unix$ pkill -HUP syslogd

Example 3: Give detailed information on all xterm processes:

unix$ ps -fp $(pgrep -d, -x xterm)

Example 4: Make all netscape processes run nicer:

unix$ renice +4 ‘pgrep netscape‘


0      One or more processes matched the criteria.

1      No processes matched.

2      Syntax error in the command line.

3      Fatal error: out of memory etc.


The process name used for matching is limited to the 15 characters present in the output of /proc/pid/stat.   Use the -f option to match against the complete command line, /proc/pid/cmdline.

The running pgrep or pkill process will never report itself as a match.


The options -n and -o and -v can not be combined.  Let me know if you need to do this.

Defunct processes are reported.


ps(1) regex(7) signal(7) killall(1) skill(1) kill(1) kill(2)


pkill and pgrep were introduced in Sun’s Solaris 7.  This implementation is fully compatible.


Kjetil Torgrim Homme <>

Albert Cahalan <> is the current maintainer of the procps package.

Please send bug reports to <>

From Linux User’s Manual.

Eric Z Ma

Eric is a father and systems guy. Eric is interested in building high-performance and scalable distributed systems and related technologies. The views or opinions expressed here are solely Eric's own and do not necessarily represent those of any third parties.

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