Will the linux “shutdown” command allow a parameter to determine the pause between sending SIGTERM and SIGKILL?

Question

The man page seems to indicate no. There is /etc/rc.d/init.d/halt on Fedora. It has a hard coded pause in it, but there's got to be a better way than to change that script. Any help would be appreciated.

Answer 1

The manpage on my system has:

-t sec Tell  init(8)  to  wait sec seconds between sending
processes the warning and  the kill signal, before changing 
to another runlevel.

(This is probably a more appropriate question for serverfault)

Answer 2

In order to have a specific delay between SIGTERM and SIGKILL, you could specify three commands in a script as root

kill -SIGTERM -1
sleep 20
kill -SIGKILL -1

to

• send SIGTERM to all processes (but 1),
• wait for 20 seconds, then
• send the -9 signal to kill immediately the remaining processes,

but it would kill your own processes, your shell interpreter...
Developing a script (e.g. in Perl) to list all processes, then to kill only the processes that do not harm your own script, and start it within nohup to attach it to the father-of-all 1 process, would do the job.

Another solution is to download the source of shutdown (or halt) and see how it works - adding a fixed or optional delay between the sending of the two signals shouldn't be too hard.