7. Kill (Terminate)

Lesson Content

You can send signals that terminate processes, such a command is aptly named the kill command.

$ kill 12445

The 12445 is the PID of the process you want to kill. By default it sends a TERM signal. The SIGTERM signal is sent to a process to request its termination by allowing it to cleanly release its resources and saving its state.

You can also specify a signal with the kill command:

$ kill -9 12445

This will run the SIGKILL signal and kill the process.

Differences between SIGHUP, SIGINT, SIGTERM, SIGKILL, SIGSTOP?

These signals all sound reasonably similar, but they do have their differences.

• SIGHUP - Hangup, sent to a process when the controlling terminal is closed. For example, if you closed a terminal window that had a process running in it, you would get a SIGHUP signal. So basically you’ve been hung up on
• SIGINT - Is an interrupt signal, so you can use Ctrl-C and the system will try to gracefully kill the process
• SIGTERM - Kill the process, but allow it to do some cleanup first
• SIGKILL - Kill the process, kill it with fire, doesn’t do any cleanup
• SIGSTOP - Stop/suspend a process

Exercise

Kill some processes using different signals.

Quiz Question