parallel

#!/usr/bin/env bash
#
# Bash script to execute multiple instances of a specific program in parallel.
#
# This script is inspired by http://stackoverflow.com/questions/356100/how-to-wait-in-bash-for-several-subprocesses-to-finish-and-return-exit-code-0
# and by http://www.gnu.org/software/parallel/
#
# Killing the child processes can be difficult if you only have the PID of the parent parallel script. Please see
# http://stackoverflow.com/questions/392022/best-way-to-kill-all-child-processes/33556110#33556110

OS=`uname -s`
MACHINE=`uname -m`

COMMAND=$1
ARGS=`echo $2 | tr ',' ' '`

if [ -z "$COMMAND" ] ; then
cat << EOF

Use as:
  parallel <command> <arg1,arg2,arg3>

This will start in parallel
  command arg1
  command arg2
  command arg3

EOF
exit
fi

if [ -z "$ARGS" ] ; then
$COMMAND
else
if [ $OS = Linux ] ; then
echo $ARGS | xargs -IARG -d " " -n 1 -P 16 $COMMAND ARG
elif [ $OS = Darwin ] ; then
echo $ARGS | xargs -IARG -n 1 -P 16 $COMMAND ARG
fi
fi