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

Examples (TL;DR)


pgrep [options] pattern
pkill [options] pattern


pgrep looks through the currently running processes and lists the process IDs which match 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.


--signal signal

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

-c, --count

Suppress normal output; instead print a count of matching processes.  When count does not match anything, e.g. returns zero, the command will return non-zero value.

-d, --delimiter delimiter

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

-f, --full

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

-g, --pgroup 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, --group gid,...

Only match processes whose real group ID is listed.  Either the numerical or symbolical value may be used.

-i, --ignore-case

Match processes case-insensitively.

-l, --list-name

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

-a, --list-full

List the full command line as well as the process ID. (pgrep only.)

-n, --newest

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

-o, --oldest

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

-P, --parent ppid,...

Only match processes whose parent process ID is listed.

-s, --session 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, --terminal term,...

Only match processes whose controlling terminal is listed.  The terminal name should be specified without the "/dev/" prefix.

-u, --euid euid,...

Only match processes whose effective user ID is listed.  Either the numerical or symbolical value may be used.

-U, --uid uid,...

Only match processes whose real user ID is listed.  Either the numerical or symbolical value may be used.

-v, --inverse

Negates the matching.  This option is usually used in pgrep's context.  In pkill's context the short option is disabled to avoid accidental usage of the option.

-w, --lightweight

Shows all thread ids instead of pids in pgrep's context.  In pkill's context this option is disabled.

-x, --exact

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

-F, --pidfile file

Read PID's from file.  This option is perhaps more useful for pkill than pgrep.

-L, --logpidfile

Fail if pidfile (see -F) not locked.

--ns pid

Match processes that belong to the same namespaces. Required to run as root to match processes from other users. See --nslist for how to limit which namespaces to match.

--nslist name,...

Match only the provided namespaces. Available namespaces: ipc, mnt, net, pid, user,uts.

-V, --version

Display version information and exit.

-h, --help

Display help and exit.



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


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

$ pgrep -u root named

Example 2: Make syslog reread its configuration file:

$ pkill -HUP syslogd

Example 3: Give detailed information on all xterm processes:

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

Example 4: Make all chrome processes run nicer:

$ renice +4 $(pgrep chrome)

Exit Status


One or more processes matched the criteria. For pkill the process must also have been successfully signalled.


No processes matched or none of them could be signalled.


Syntax error in the command line.


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.

See Also

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


Kjetil Torgrim Homme

Reporting Bugs

Please send bug reports to

Referenced By

fuser(1), killall(1), pidof(1), pmap(1), ps(1), pslog(1), pwdx(1), skill(1), x11vnc(1).

The man page pkill(1) is an alias of pgrep(1).

2017-12-22 procps-ng