built-in Bash commands
builtin (built-in Bash command)
The builtin Bash command manual page and help. The command executes the Bash built-in command specified in its parameter. If there is an external command with the same name, builtin will still run only the builtin. So by using this command, you can be sure that you are only running built-in commands.
kill (built-in Bash command)
Manual page and help for the kill linux command. The kill program sends the specified signal to the specified process. If no signal is specified, the TERM signal is sent. This fires processes that do not receive this signal. If necessary, the KILL (9) signal can be used, which is not available, so it will definitely stop the process.