Table of Contents

The pkill command sends a signal to processes selected by name or pattern.

It combines process matching (similar to pgrep) with signaling behavior (similar to kill).

Overview

By default, pkill sends SIGTERM. Use explicit options when you need a different signal or tighter matching.

Syntax

pkill [options] pattern

Command Quick Reference

Command Purpose
pkill nginx Send TERM to matching nginx processes
pkill -x nginx Exact process name match
pkill -f "python worker.py" Match full command line
pkill -HUP nginx Send HUP (often reload)
pkill -u www-data php-fpm Signal matching processes owned by user

Core Workflows

Graceful Stop by Name

pkill -TERM -x nginx

Reload a Daemon (When Supported)

pkill -HUP -x nginx

Signal by Full Command Pattern

pkill -f "node server.js"

Restrict by User

pkill -u appuser -f "python worker.py"

Useful Options

Option Meaning
-f Match full command line
-x Exact process name match
-u Match by effective user ID/name
-SIGNAL Signal shorthand (example: -KILL)
-s <signal> Signal by name
-n Match newest process only
-o Match oldest process only

Examples

pkill -f my-worker
pkill -TERM -x sshd
pkill -KILL -f "stuck-process"

Troubleshooting

Unexpected Processes Were Signaled

Pattern was too broad. Validate matches first with:

pgrep -af <pattern>

Then tighten with -x, -u, or a more specific -f string.

Permission Denied

You need ownership of target processes or elevated privileges.

Best Practices

  1. Validate with pgrep -af before running broad pkill patterns.
  2. Prefer graceful signals (TERM, HUP) before KILL.
  3. Use exact matching (-x) when possible.
  4. For system services, prefer systemctl over direct signaling.
  • pgrep: Preview process matches
  • kill: Signal specific PIDs
  • systemctl: Service-oriented control for systemd units
Edit this page