$ Linux Command

Processes

skill

Send signals to processes based on name or criteria.

processsignalkillname

Additional Notes

skill sends signals to processes matching a given criteria, such as process name, terminal, user, or process ID. It is an older utility that predates pgrep and pkill, and is now largely superseded by those tools. The name comes from "skill" as in "send a signal to kill," not as in proficiency.

skill can match processes by command name, terminal device, user ID, or process ID. It is useful for bulk operations like terminating all processes belonging to a specific user or started from a specific terminal.

Syntax

skill [signal] [options] process_criteria

Parameters

  • signal: The signal to send (by name like TERM, KILL, HUP or by number like 9, 15).
  • process_criteria: Criteria to match processes (name, terminal, user, etc.).

Common Options

  • -l, --list: List all signal names.
  • -i, --interactive: Ask for confirmation before sending each signal.
  • -w, --warnings: Show warning messages.
  • -n, --no-warnings: Suppress warning messages.
  • -v, --verbose: Show verbose output.
  • -t term: Match processes attached to a specific terminal.
  • -u user: Match processes owned by a specific user.
  • -p pid: Match a specific process ID.
  • -c command: Match processes by command name (default matching mode).

Examples

skill -KILL -u bob

Kill all processes owned by user bob.

skill -TERM -t pts/0

Send SIGTERM to all processes attached to terminal pts/0.

skill -HUP nginx

Send SIGHUP to all processes named nginx.

skill -9 myprogram

Force-kill all processes named myprogram.

skill -l

List all available signal names.

Practical Notes

  • skill is considered obsolete. Use pkill or killall instead.
  • The command matches the process name as reported by ps, not the full command line.
  • Without a signal prefix (like -TERM or -9), the default signal is SIGTERM (15).
  • Be careful with -KILL (-9) as processes cannot clean up resources when killed this way.
  • Some distributions no longer include skill by default; it is part of the util-linux package.