Nice reload of config with sendmail

[Logan Shaw]

On Wed, 12 Jul 2006, Arthur Sherman wrote:
>>> 	What is the less disturbing way to reload the MS/Sendmail config on a
>>> server?

James wrote:
>> Personally, I just HUP the MS parent[1] (which kills all the
>> kids before
>> spawning a new brood of rug-rats) and "killall -HUP sendmail".  I put
>> all that in a bash script and dumped it in /root/bin/mail-reload.sh

> Could you post it here?
> I would like to see it.

I find the easiest way to go in search of pids like this is to
use the formatting capabilities that "ps" has on many versions
of Unix, combined with awk.  For example, on Linux:

 	ps -e -o pid,ppid,comm |
 	    awk '$3 == "MailScanner" && $2 == 1 { print $1 }'

That prints pid, parent pid, and command only as output from
"ps".  Then awk checks for processes whose name is "MailScanner"
and whose parent is "1" (the init process).  That should be
the master MailScanner process.  From there, it's just a matter
of killing that one pid:

 	kill `ps -e -o pid,ppid,comm |
 	    awk '$3 == "MailScanner" && $2 == 1 { print $1 }'`

Or the more elaborate and verbose version:

 	ps -e -o pid,ppid,comm |
 	    awk '$3 == "MailScanner" && $2 == 1 { print $1 }' |
 	    while read pid
 	    do
 		echo "Killing this process:"
 		ps -f -p "$pid"
 		kill "$pid"
 	    done

Or the more elaborate and verbose and paranoid version:

 	ps -e -o pid,ppid,comm |
 	    awk '$3 == "MailScanner" && $2 == 1 { print $1 }' |
 	    while read pid
 	    do
 		echo "Kill this process?"
 		ps -f -p "$pid"

 		# gotta redirect stdin here, else it will come from pipe
 		read response < /dev/tty
 		case "$response" in
 		y|Y)
 		    echo "killing $pid"
 		    kill "$pid"
 		    ;;
 		*)
 		    echo "leaving $pid alone"
 		    ;;
 		esac
 	    done

Of course, your script will want a delay in there to be sure
that MailScanner really has exited.  If you want to do the
really obnoxious thing, you could always do this:

 	#! /bin/sh

 	get_mailscanner_pid ()
 	{
 	    ps -e -o pid,ppid,comm |
 		awk '$3 == "MailScanner" && $2 == 1 { print $1 }'
 	}

 	stop_ms ()
 	{
 	    p=$1
 	    echo "Killing $p."
 	    kill "$p"
 	    echo

 	    echo "Waiting for $p to exit..."
 	    while ps -p "$p"
 	    do
 		sleep 3
 	    done

 	    echo "$p has exited."
 	}

 	start_ms ()
 	{
 	    echo "Restarting."
 	    /opt/MailScanner/bin/check_mailscanner
 	}

 	ms_pid=`get_mailscanner_pid`
 	stop_ms "$ms_pid"
 	start_ms "$ms_pid"

By the way, I've always used just "kill" and not "kill -HUP"
with MailScanner and this seems to work fine -- it changes its
argv[0] string to indicate it's gracefully exiting (killing
children -- bwahahaha), so I'm not sure if SIGHUP matters
or not.

   - Logan