Shell Programming and Scripting

maxProc=5
while [[ filesStillExist ]]
do
  for procNo in {1..$maxProc}
  do
    FileProcessor > /dev/null &
  done
  wait
done

maxproc=5
set --
while [[ condition ]]
do
        process &

        set -- $* $!
        [ "$#" -gt maxproc ] && wait "$1" && shift
done

wait

max_jobs=5
rm -f .stop_jobs
while [ ! -f .stop_jobs ]
do
   jobs -l | wc -l | read current_job_count
   [[ $current_job_count -lt $max_jobs ]] && { run_process & 2>/dev/null }
   sleep 1
done

#!/bin/ksh

echo "Process started on: (`date`)"
\rm parallel.log > /dev/null


n=`ls -al *.csv | wc -l | cut -d ' ' -f 1` #number of files

i=1
while [[ $i -le $n ]]
do
  for noProc in {1..$1} # $1 is maximum number of processes
  do
        file=`ls -a *.csv | head -$i | tail -1 | xargs basename` #take just the name of the file
        echo "Processing file: " $file " ==> " $i " of " $n # E.g. Processing file: ABC.csv ==> 4 of 154
        ./ProcessFile > /dev/null &
        let i=i+1
        if [ $i -gt $n ]; then
                break # to stop in case total number of files does not divide exactly to the maximum number of processes
        fi
  done
  wait
  echo "=================== Finished batch ==================="
done

echo "Process finished on: (`date`)"

$ set -- a b c
$ echo $@

a b c

$ set -- "$@" d
$ echo $@

a b c d

$ shift
$ echo $@

b c d

$ echo $1

b

$ echo $#

3

$

maxproc=5
i=0

# Count files
set -- *.csv
FILES="$#"

# Blank $1 $2 ...
set --


let i=1
for FILE in *.csv
do
        echo "Processing ${FILE/.csv}, $i/$FILES"
        let i=i+1

        ./ProcessFile "$FILE" >/dev/null &

        # Turn $1=pida $2=pidb $3=pidc $4=pidd, into
        # $1=pida $2=pidb $3=pidc $4=pidd $5=pide
        set -- "$@" $!

        # Shift removes $1 and moves the rest down, so you get
        # $1=pidb $2=pidc $3=pidd $3=pide
        # $# is the number of options.
        [ "$#" -ge $maxproc ] && wait $1 && shift
done

# Wait for ALL remaining processes, not just one specific one.
wait

file=`ls -a *.csv | head -$i | tail -1 | xargs basename` #take just the name of the file