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.