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kill Cheatsheet

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kill sends signals to processes. Terminate, pause, resume, or control processes by PID. Essential for process management and system administration.

Basic Usage

  • kill PID - Send TERM signal (default)
  • kill -9 PID - Force kill (SIGKILL)
  • kill -15 PID - Terminate gracefully (SIGTERM)
  • kill -HUP PID - Hangup signal (reload)
  • killall process_name - Kill by name
  • pkill pattern - Kill by pattern

Common Signals

  • SIGHUP (1) - Hangup, reload configuration
  • SIGINT (2) - Interrupt (Ctrl+C)
  • SIGQUIT (3) - Quit with core dump
  • SIGTERM (15) - Terminate gracefully
  • SIGKILL (9) - Force kill (cannot be caught)
  • SIGSTOP (19) - Stop process
  • SIGCONT (18) - Continue stopped process

Signal Syntax

  • kill -SIGTERM PID - Signal name
  • kill -15 PID - Signal number
  • kill -TERM PID - Short name
  • kill -l - List all signals
  • kill -L - List signals with numbers

Killing Multiple Processes

  • kill PID1 PID2 PID3 - Multiple PIDs
  • killall process_name - All processes by name
  • pkill -f pattern - Match full command line
  • kill -9 $(pgrep process) - Kill by pgrep

Common Examples

Terminate Process

kill 1234

Send TERM signal to PID.

Force Kill

kill -9 1234

Force kill unresponsive process.

Reload Process

kill -HUP 1234

Send hangup signal (reload config).

Kill by Name

killall firefox

Kill all firefox processes.

Kill by Pattern

pkill -f "python script.py"

Kill matching processes.

Stop Process

kill -STOP 1234

Pause process.

Continue Process

kill -CONT 1234

Resume stopped process.

List Signals

kill -l

Show all available signals.

Kill Process Tree

pkill -P 1234

Kill process and children.

Kill User Processes

pkill -u username

Kill all processes for user.

Tips

  • Use SIGTERM first for graceful shutdown
  • Use SIGKILL (-9) only when necessary
  • SIGKILL cannot be caught or ignored
  • Use killall or pkill for convenience
  • Check process with ps before killing
  • Use -HUP to reload configurations
  • Essential for process management
  • Be careful with killall on production