PGREP(1) User Commands PGREP(1)
NAME
pgrep, pkill, pidwait - look up, signal, or wait for processes based on
name and other attributes
SYNOPSIS
pgrep [options] pattern
pkill [options] pattern
pidwait [options] pattern
DESCRIPTION
pgrep looks through the currently running processes and lists the
process IDs which match the selection criteria to stdout. All the cri‐
teria 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.
pidwait will wait for each process instead of listing them on stdout.
OPTIONS
-signal
--signal signal
Defines the signal to send to each matched process. Either the
numeric or the symbolic signal name can be used. In pgrep or pid‐
wait mode this has no effect unless used in conjunction with
--require-handler to filter to processes with a userspace signal
handler present for a particular signal.
-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. Note that for pkill
and pidwait, the count is the number of matching processes, not
the processes that were successfully signaled or waited for.
-d, --delimiter delimiter
Sets the string used to delimit each process ID in the output (by
default a newline). (pgrep only.)
-e, --echo
Display name and PID of the process being killed. (pkill 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, pkill’s, or pidwait’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.
-O, --older secs
Select processes older than secs.
-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, pkill’s, or pidwait’s own ses‐
sion 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 or
pidwait’s context. In pkill’s context the short option is dis‐
abled to avoid accidental usage of the option.
-w, --lightweight
Shows all thread ids instead of pids in pgrep’s or pidwait’s con‐
text. In pkill’s context this option is disabled.
-x, --exact
Only match processes whose names (or command lines if -f is spec‐
ified) exactly match the pattern.
-F, --pidfile file
Read PIDs from file. This option is more useful for pkill or
pidwait than pgrep.
-L, --logpidfile
Fail if pidfile (see -F) not locked.
-r, --runstates D,R,S,Z,...
Match only processes which match the process state.
-A, --ignore‐ancestors
Ignore all ancestors of pgrep, pkill, or pidwait. For example,
this can be useful when elevating with sudo or similar tools.
-H, --require-handler
Only match processes with a userspace signal handler present for
the signal to be sent.
--cgroup name,...
Match on provided control group (cgroup) v2 name. See cgroups(8)
--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.
-q, --queue value
Use sigqueue(3) rather than kill(2) and the value argument is
used to specify an integer to be sent with the signal. If the re‐
ceiving process has installed a handler for this signal using the
SA_SIGINFO flag to sigaction(2), then it can obtain this data via
the si_value field of the siginfo_t structure.
-V, --version
Display version information and exit.
-h, --help
Display help and exit.
OPERANDS
pattern
Specifies an Extended Regular Expression for matching against the
process names or command lines.
EXAMPLES
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
0 One or more processes matched the criteria. For pkill and pid‐
wait, one or more processes must also have been successfully sig‐
nalled or waited for.
1 No processes matched or none of them could be signalled.
2 Syntax error in the command line.
3 Fatal error: out of memory etc.
NOTES
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. Threads may not
have the same process name as the parent process but will have the same
command line.
The running pgrep, pkill, or pidwait process will never report itself as
a match.
The -O --older option will silently fail if /proc is mounted with the
subset=pid option.
BUGS
The options -n and -o and -v can not be combined. Let me know if you
need to do this.
Defunct processes are reported.
pidwait requires the pidfd_open(2) system call which first appeared in
Linux 5.3.
SEE ALSO
ps(1), regex(7), signal(7), sigqueue(3), killall(1), skill(1), kill(1),
kill(2), cgroups(8).
AUTHOR
Kjetil Torgrim Homme
REPORTING BUGS
Please send bug reports to procps@freelists.org
procps‐ng 2023‐01‐16 PGREP(1)