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

Kathryn Hogg kjh at flyballdogs.com
Fri Apr 14 05:56:12 EST 2006

Carla Schroder wrote:
> Is there a reference written in actual English that explains the kill
> command?
> 'man kill' is rather too terse to be useful to a noob.  I want to know
> what
> all the options mean, and when to use them. All these years of seeing
> mysterious references like "send a SIGHUP", well, it's time to learn what
> the
> silly things mean.

all kill does is send signals to a process (or processes).  The signal(7)
man page gives a good overview of the standard signal.

Now the tricky part is that what each of those signals mean can be
application development.  As you mentioned, a somewhat common convention
is to reread config files upon receipt of a SIGHUP (kill -HUP $pid).  Of
course you need to read that applications documentation to find out if
thats what it does.

In my code at work, SIGUSR2 causes any of our processes to generate a
really nice dump (kill -USR2 $pid).


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