killall command

killall - kill processes by name

The killall command in Linux is a utility used to terminate processes by name rather than by process ID (PID), unlike the kill command. It’s a convenient way to stop all instances of a program (e.g., a crashed application) without needing to look up PIDs individually.

Usage: killall [options] [name...]

• name: The name of the process(es) to terminate (e.g., firefox, bash).
• options: Flags to modify behavior or specify signals.

Examples

• Basic Usage

  Send the default signal (SIGTERM) to all processes with a given name.

  killall firefox
  • Terminates all running Firefox processes.
  • SIGTERM requests graceful shutdown, allowing cleanup.

• Forcing Termination

  Use -9 (or -SIGKILL) to forcefully stop processes.

  killall -9 firefox
  • Sends SIGKILL to all Firefox processes, stopping them immediately without cleanup.
  • Use this when SIGTERM fails.

• Specifying Signals

  Like kill, killall supports various signals using -SIGNALNAME or -NUMBER.

  Common Signals:

  Signal	Number	Description
  SIGTERM	15	Terminate gracefully (default)
  SIGKILL	9	Force immediate termination
  SIGHUP	1	Hang up (reload config for some daemons)
  SIGINT	2	Interrupt (like Ctrl+C)

  killall -SIGHUP nginx
  • Sends SIGHUP to reload Nginx configuration.

  With Number:

  killall -1 nginx
  • Same as above.

• Case-Insensitive Matching

  Use -i to ignore case when matching process names.

  killall -i FIREFOX
  • Kills processes named firefox, Firefox, or FIREFOX.

• Exact Match

  Use -e to require an exact process name match (avoids partial matches).

  killall -e bash
  • Only kills bash, not mybashscript or similar.

• Verbose Output

  Use -v to see which processes are being killed.

  killall -v firefox
  • Output: killed firefox(1234), killed firefox(5678).

• Listing Signals

  Use -l to list available signals.

  killall -l
  • Output (partial): HUP INT QUIT KILL TERM ....

To get help related to the killall command use --help option

$ killall --help
Usage: killall [OPTION]... [--] NAME...
       killall -l, --list
       killall -V, --version

  -e,--exact          require exact match for very long names
  -I,--ignore-case    case insensitive process name match
  -g,--process-group  kill process group instead of process
  -y,--younger-than   kill processes younger than TIME
  -o,--older-than     kill processes older than TIME
  -i,--interactive    ask for confirmation before killing
  -l,--list           list all known signal names
  -q,--quiet          don't print complaints
  -r,--regexp         interpret NAME as an extended regular expression
  -s,--signal SIGNAL  send this signal instead of SIGTERM
  -u,--user USER      kill only process(es) running as USER
  -v,--verbose        report if the signal was successfully sent
  -V,--version        display version information
  -w,--wait           wait for processes to die
  -n,--ns PID         match processes that belong to the same namespaces
                      as PID
  -Z,--context REGEXP kill only process(es) having context
                      (must precede other arguments)

For more details, check the manual with man killall