skill

Send a signal to processes that match selection criterias.

skill [signal to send] [options] process selection criteria

-t The next string is a terminal (tty or pty)
-u The next string is a username
-p The next string is a process ID
-c The next string is a command name

skill -9 -u khai -c httpd

Kill users on new-style PTY devices:

skill -KILL -v /dev/pts/*

Stop 3 users:

skill -STOP viro lm davem