User's cron job creates zombie process on 5.3

[Rob]

Hi,

As a regular user, I have a cron job; 'crontab -l' says:

-----------------------------------------
SHELL=/bin/sh
MAILTO=""

# run at bootup and then every 5 minutes
@reboot     $HOME/bin/ssh_tunnel
*/5 * * * * $HOME/bin/ssh_tunnel
-----------------------------------------

The ssh_tunnel is an sh-script, which checks whether a particular
ssh-tunnel still exists, and if not regenerates it, as follows:

   #!/bin/sh
   #---------------- ssh_tunnel script ---------
   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>

The "STARTED" time, is when the PC rebooted last time.

When I remove the cronjob and reboot, the zombie process is not
created anymore. Any idea what's the problem here?

Thanks,
Rob.