[Techtalk] sighup, kill -9, sigkill, and all those related things

Kathryn Hogg kjh at flyballdogs.com
Fri Apr 14 06:46:56 EST 2006

Cynthia Kiser wrote:
> But it still left me wondering about the difference between
> kill's 1-3.

from "man 7 signal"

Signal     Value     Action   Comment
SIGHUP        1       Term    Hangup detected on controlling terminal
                              or death of controlling process
SIGINT        2       Term    Interrupt from keyboard
SIGQUIT       3       Core    Quit from keyboard

Hangup detected on controlling terminal usually means that someone has
logged out.  If you start a background process and log out, the background
process will terminate.  Thats why the nohup command was invented many
years go ago.

If you run "stty -a" you'll see what keys maps to different keyboard events.
I have intr=^C and quit=^\ where ^ = control.

If I have a running process and type Ctrl-C, it will get SIGINT which
normally causes it to terminate.  If I type Ctrl-\, it will generate a
core file and exit.

Applications can override most default signal handlers (SIGTERM cannot)
via fun functions like sigaction().


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