Function to run a command in parallel batches

loop.sh

#!/usr/bin/env bash

loop() {
  total_runs=$1
  runs_per_loop=$2
  shift
  shift

  int_regex='^[0-9]+$'

  if ! [[ $total_runs =~ $int_regex ]] ; then
    echo "Usage: loop <total runs> <runs per loop> <command>"
    return
  fi
  if ! [[ $runs_per_loop =~ $int_regex ]] ; then
    echo "Usage: loop <total runs> <runs per loop> <command>"
    return
  fi

  number_of_loops=$((total_runs / runs_per_loop))
  remainder=$((total_runs % runs_per_loop))

  if [[ "$total_runs" -gt "$runs_per_loop" ]]; then
    for loop in $(seq 0 $((number_of_loops - 1))); do
      for loop_run_num in $(seq 1 $runs_per_loop); do
        $@
      done

      wait 2>/dev/null
    done
  fi

  if [[ "$remainder" -ne 0 ]]; then
    for loop_run_num in $(seq 1 $remainder); do
      $@
    done

    wait 2>/dev/null
  fi
}