User's cron job creates zombie process on 5.3

[Rob]

Raymond Wiker wrote:
> Peter Jeremy writes:
>  > On Wed, 2005-Jan-19 09:16:59 +0900, Rob Lahaye wrote:
>  > >  tunnel="-L 55110:localhost:110 pop3.univ.net"
>  > >  tunnel_up=`pgrep -f -- "${tunnel}"`
>  > >  [ "${tunnel_up}" = "" ] && /usr/bin/ssh -N -f ${tunnel}
>  > 
>  > >It works beautifully, but why does this also generate one zombie process:
>  > > USER  PID %CPU %MEM   VSZ  RSS  TT  STAT STARTED      TIME COMMAND
>  > > rob   655  0.0  0.0     0    0  ??  Z    Sat02PM   0:00.01 <defunct>
>  > 
>  > You get a zombie when a process has exited and the parent hasn't issued
>  > a wait(2) (or SIG_IGN'd SIGCHLD).  Have a look at what the parent process
>  > is and that might give you an idea as to what is going wrong.
> 
>         Ancient Perl did not collect for children started via the
> backtick operator - is this a possible issue for /bin/sh as well? It
> should be harmless to call wait just after the use of the backtick
> operator above; does that change anything? I.e:
> 
>         tunnel_up=`pgrep -f -- "${tunnel}"`; wait
> 
>         To see the parent pid, add "-O ppid" to the arguments to ps;
> e.g,
> 
> ps axww -O ppid

Adding the "wait" here does not help at all.

When I verify the parent process I have this:

   PID  PPID  TT  STAT      TIME COMMAND          USER   %CPU %MEM   VSZ  RSS STARTED
   423   417  ??  I      0:00.00 cron: running jo root    0.0  0.2  1360 1148 11:38PM
   425   423  ??  Z      0:00.00 <defunct>        lahaye  0.0  0.0     0    0 11:38PM


So PID 423 "cron: running job (cron)" is the parent of my <defunct> zombie.

After playing with commenting out lines, I found out that the ssh call is the
reason for the zombie:  "/usr/bin/ssh -N -f -L 55110:localhost:110 pop3.univ.net"

Then I tried exec  : "exec /usr/bin/ssh -N -f ..."
And I also tried & : "/usr/bin/ssh -N -f ... &"
Both to no avail.

What else can I try, and why is this ssh command causing a zombie process when
called from cron?

Rob.