When ever I need to keep a job running I use a sub shell type structure

#!(bash|ksh|sh)
<set up environment>
(while true
do
<perl script>
# brief delay to ensure everything is shutdown
sleep 60
done) &
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The subshell itself is backgrounded rather than just the Perl script.

I'm sure this can be adapted to starting up n copies of <perl script> maybe a little loop that will fire up multiple subshells. Note I'm not a BASH expert

#!(bash|ksh|sh)
<set up environment>
for I in {1..n};
do
   (while true
      do
      <perl script> $I
      # brief delay to ensure everything is shutdown
      sleep 60
    done) &;
done
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