kill
General Information
kill is the command to send signals to processes.
Checklist
- Distro(s): Any
Kill Signals
List kill signals
kill -l
Some of the more often used signals:
| Signal # | Signal Name | Description | Can process ignore? |
|---|---|---|---|
| 1 | HUP | Hangup (daemons re-read config file) | Yes |
| 9 | KILL | Kill immediately, kernel level | No |
| 15 | TERM | Software termination request, process cleans up and exits (default) | Yes |
Kill Syntax
kill [-signal] pid
- -signal : can be the signal number or name
- pid : process id of the target
If -signal is ommited, kill sends -15 (TERM) by default.
Kill Examples
Ask apache to re-read its configuration file after changes have been made. (Assumes httpd is pid 2123)
kill -1 2123
or
kill -HUP 2123
Ask apache to terminate gracefully:
kill 2123
Tell the kernel to immediately kill apache:
kill -9 2123
pkill
Kill process by name (instead of PID)
pkill httpd
- Kills all process ids named httpd, sending signal 15 (SIGTERM)
Remove a user's ssh session (kick user off system)
pkill -u rjones sshd
Kill all processes started from a specific terminal
pkill -t pts/1
- This does NOT kick them off the system, only kills their running programs started from that session.