Very Computer

I have written a short sh script to check if a process is running and
start it if it isn't. The process looks for a file (which may or may not
exist) that contains the pid, checks to see if the process is running:

if [ -f $pidfile ]; then
        $pid=`cat $pidfile`
        $check=`ps x | grep "^ *$pid"`
        if [ -z "$check" ]; then
                $progname > /dev/null 2>&1
        fi
else
  $progname > /dev/null 2>&1
fi

This works great from the command line, but fails if I put it in the
crontab, and cron doesnt mail me anything.  The system is NetBSD. Any
suggestions?
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Quote:>I have written a short sh script to check if a process is running and
>start it if it isn't. The process looks for a file (which may or may not
>exist) that contains the pid, checks to see if the process is running:

>if [ -f $pidfile ]; then
>    $pid=`cat $pidfile`
>    $check=`ps x | grep "^ *$pid"`
>    if [ -z "$check" ]; then
>            $progname > /dev/null 2>&1
>    fi
>else
>  $progname > /dev/null 2>&1
>fi

>This works great from the command line, but fails if I put it in the
>crontab, and cron doesnt mail me anything.  The system is NetBSD. Any
>suggestions?

I'm surprised that it works from the command line.

Quote:>    $pid=`cat $pidfile`
>    $check=`ps x | grep "^ *$pid"`

should be:
        pid=`cat $pidfile`
        check=`ps x | grep "^ *$pid"`
You don't need $ before a variable name when you assign a value to that
variable.  If you do:
        $pid=`cat $pidfile`
creates a new variable whose name is the previous contents of $pid.

-/-

Try:

if [ -f $pidfile ]; then
        pid=`cat $pidfile`
        check=`ps x | grep "^ *$pid"`
        if [ -z "$check" ]; then
                $progname > /dev/null 2>&1
        fi
else
  $progname > /dev/null 2>&1
fi

And: watch out for unset variables ($pidfile, $pid, $progname, ...).

Marcel
--
____   __ . . __

| | | |__  _| | | National Aerospace Laboratory NLR  fax: +31 20 5113210

: >
: > I have written a short sh script to check if a process is running and
: > start it if it isn't. The process looks for a file (which may or may not
: > exist) that contains the pid, checks to see if the process is running:
: >
: > if [ -f $pidfile ]; then
: >         $pid=`cat $pidfile`
: >         $check=`ps x | grep "^ *$pid"`
: >         if [ -z "$check" ]; then
: >                 $progname > /dev/null 2>&1
: >         fi
: > else
: >   $progname > /dev/null 2>&1
: > fi
: -/-

: Try:

: if [ -f $pidfile ]; then
:         pid=`cat $pidfile`
:         check=`ps x | grep "^ *$pid"`
:         if [ -z "$check" ]; then
:                 $progname > /dev/null 2>&1
:         fi
: else
:   $progname > /dev/null 2>&1
: fi

: And: watch out for unset variables ($pidfile, $pid, $progname, ...).

: Marcel
: --
: ____   __ . . __

: | | | |__  _| | | National Aerospace Laboratory NLR  fax: +31 20 5113210

kill -0 $pid is much more efficient than ps|grep:

if [ -f $pidfile ]; then
    pid=`cat $pidfile`
    # kill the pid with -0
    # an error indicates that it has died
    kill -0 $pid >/dev/null 2>&1 || $progname > /dev/null 2>&1
else
    $progname > /dev/null 2>&1
fi

--
Dan Mercer

Opinions expressed herein are my own and may not represent those of 3M.