Shell Programming and Scripting

#!/bin/ksh
PROCS=6
SLEEP=20
while read LINE
do
     while true
     do
         NUM=$(jobs | wc -l)
         echo NUM=$NUM
         if [ $NUM -lt $PROCS ]
         then
             stuff "$LINE" &
             break
         else
             sleep $SLEEP
         fi
    done
done < textfile
# wait for ALL remaining processes
wait

       --halt-on-error <0|1|2>
       --halt <0|1|2>
       -H <0|1|2> (-H will be retired 20120122)
                0  Do not halt if a job fails. Exit status will be the number
                   of jobs failed. This is the default.

                1  Do not start new jobs if a job fails, but complete the
                   running jobs including cleanup. The exit status will be the
                   exit status from the last failing job.

                2  Kill off all jobs immediately and exit without cleanup. The
                   exit status will be the exit status from the failing job.

errfile="errorfile"
rm "$errfile"
while read LINE && [ ! -f "$errfile" ]
do
...
  while [ ! -f "$errfile" ]
  do
...
    (stuff "$LINE" || echo "bad exit status" > "$errfile") &
...