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📖 NAME

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

🚀 Quick Reference

Use Case	Command	Description
🔍 Find PID by exact process name	pgrep -x sshd	Lists PIDs of processes named exactly sshd
🔍 Find PID of a daemon owned by root	pgrep -u root named	Lists PIDs of named processes owned by root
🔍 Count matching processes	pgrep -c httpd	Prints number of httpd processes
🔍 List process name and PID	pgrep -l sshd	Shows both name and PID
🔍 List full command line and PID	pgrep -a process	Shows full command line and PID
🔍 Match against full command line	pgrep -f "pattern"	Matches pattern against full command line
🔍 Case-insensitive match	pgrep -i process	Ignores case when matching
🔍 Invert match	pgrep -v process	Lists processes not matching pattern
🔍 Most recently started process	pgrep -n bash	Selects newest matching process
🔍 Oldest process	pgrep -o bash	Selects oldest matching process
🔍 Processes with specific parent PID	pgrep -P 1234	Matches child processes of PID 1234
🔍 Processes by user (effective UID)	pgrep -u root	Matches processes owned by root
🔍 Processes by group	pgrep -G 1000	Matches processes with real group ID 1000
🔍 Processes by terminal	pgrep -t pts/0	Matches processes on terminal pts/0
🔍 Processes by session ID	pgrep -s 100	Matches processes in session 100
🔍 Processes older than N seconds	pgrep -O 3600	Matches processes older than 3600 seconds
🔍 Processes from a PID file	pgrep -F /var/run/sshd.pid	Reads PIDs from file
🔍 Thread IDs instead of PIDs	pgrep -w process	Shows all thread IDs
🔍 Processes by namespace	pgrep --ns 1	Matches processes in same namespace as PID 1
🚦 Send signal to process	pkill -HUP syslogd	Sends SIGHUP to syslogd
🚦 Kill process by name	pkill chrome	Sends SIGTERM to all chrome processes
🚦 Echo killed processes	pkill -e sshd	Displays name and PID of killed processes
🚦 Custom signal	pkill -SIGKILL process	Sends SIGKILL
⏳ Wait for processes to exit	pidwait process	Waits for all matching processes to terminate

📝 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 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.

⚙️ OPTIONS

🔧 -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 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.

🌐 --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.

ℹ️ -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 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.

📝 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.

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

🐛 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.

📚 SEE ALSO

ps(1), regex(7), signal(7), sigqueue(3), killall(1), skill(1), kill(1), kill(2)

✍️ AUTHOR

Kjetil Torgrim Homme <kjetilho AT ifi.no>

📥 REPORTING BUGS

Please send bug reports to <procps AT freelists.org>

procps-ng   2020-06-04   PGREP(1)

📖 NAME 🚀 Quick Reference 📝 SYNOPSIS 📘 DESCRIPTION ⚙️ OPTIONS 📝 OPERANDS 💡 EXAMPLES 🚪 EXIT STATUS 📝 NOTES 🐛 BUGS 📚 SEE ALSO ✍️ AUTHOR 📥 REPORTING BUGS