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Friday, April 19, 2019

killall command and signals.

killall sends a SIGTERM signal (if signal name is not specified explicitly) to all processes running any of the specified commands. 

[Syntax]
killall [options] command

killall supports regular expression matching of process names, via the -r option.

If the specified command contains slash (/) characters, the command is interpreted as a file name and processes running that particular file will be selected as signal recipients.

To make the killall operation interactive you can provide -i option which makes killall prompt for confirmation before sending signal.


Signals are software interrupts sent to a program to indicate that an important event has occurred.

You can use the options -s, --signal, and -SIGNAL options to send explicit signals.

[Example]
killall -s 9 chrome
killall -SIGKILL python

Some common signals :
SIGINT 2 - Issued if the user sends an interrupt signal (Ctrl + C).
SIGQUIT 3 - Issued if the user sends a quit signal (Ctrl + D).
SIGKILL 9 - If a process gets this signal it must quit immediately and will not perform any clean-up operations.