Spawn many processes and wait for all of them to complete

many.sh

#! /bin/bash

FAIL=0
VERBOSE=0
SLEEP="0"

# parse options
while getopts "vw:d" opt; do
  case $opt in
    v)
      VERBOSE=1
      ;;
    w)
      SLEEP=$OPTARG
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      exit 1
      ;;
  esac
done

# remove option from args
shift $(($OPTIND - 1))

# warn if not enough args
if [ $# -lt 2 ]; then
    echo "Usage: many [-v] [-w seconds] number_of_processes command [args]"
    exit
fi

NUM_PROCS=$1
shift 1

echo "Spwaning $NUM_PROCS processes, waiting $SLEEP seconds in between spawns."

T="$(date +%s)"
for (( i = 0; i < $NUM_PROCS ; i++ ))
do
    if [ $VERBOSE != "0" ]; then
        $@ &
    PIDLIST="$PIDLIST $!"
    sleep $SLEEP
    else
        $@ > /dev/null &
    PIDLIST="$PIDLIST $!"
    trap "kill $PIDLIST" SIGINT SIGTERM
    sleep $SLEEP
    fi
done

echo -en "\033[1;31mDone spawning $NUM_PROCS processes in $(($(date +%s)-T)) seconds\033[0m \n"
echo "Waiting for completion now ..."

WAIT=0
for job in $PIDLIST
do
    let WAIT+=1
    wait $job || let "FAIL+=1"
done

if [ "$FAIL" == "0" ];
then
echo "All processes completed succesfully."
else
echo "($FAIL) processes exited with an error!"
fi

T="$(($(date +%s)-T))"
echo "Time in seconds: ${T}"