pgrep, pkill, pidwait - look up, signal, or wait for processes based on name and
other attributes
pgrep [options] pattern
pkill [options] pattern
pidwait [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.
pidwait will wait for each process instead of listing them on stdout.
-
-signal
-
--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. 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 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 or pidwait'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 or
pidwait's context. In pkill's context this option is
disabled.
-
-x, --exact
- Only match processes whose names (or command lines if
-f is specified) exactly match the pattern.
-
-F, --pidfile file
- Read PIDs from file. This option is more
useful for pkillorpidwait 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.
-
--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 receiving 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.
- pattern
- 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)
- 0
- One or more processes matched the criteria. For pkill and
pidwait, one or more processes must also have been successfully signalled
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.
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.
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.
ps(1),
regex(7),
signal(7),
sigqueue(3),
killall(1),
skill(1),
kill(1),
kill(2),
cgroups(8)
Kjetil Torgrim Homme
Please send bug reports to
[email protected]