Run batches of bash things in parallel

parallel-jobs-in-batches.sh

#!/usr/bin/env bash

set -euo pipefail

if [ "$#" -ne 1 ]; then
  echo "Usage: $(basename "$0") <number-of-times-to-run-job>"
  exit 1
fi

total_runs="$1"

int_regex='^[0-9]+$'
if ! [[ $total_runs =~ $int_regex ]] ; then
  echo "Argument must be a positive integer"
  exit 1
fi

job() {
  n="$((RANDOM % 9 + 1))"
  sleep "0.$n"

  echo -e "$@"
}

runs_per_loop=10
number_of_loops=$((total_runs / runs_per_loop))
remainder=$((total_runs % runs_per_loop))

echo "number of loops: $number_of_loops"
echo "remainder: $remainder"
echo

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 $runs_per_loop); do
      num=$(((loop * runs_per_loop) + loop_run_num))
      str="loop: $loop \tloop_run_num: $loop_run_num \trun_num: $num"
      job "$str" &
    done

    wait
    echo -e "\n[$(date)] Finished $(((loop + 1) * runs_per_loop)) runs\n"
  done
fi

if [[ "$remainder" -ne 0 ]]; then
  for loop_run_num in $(seq 1 $remainder); do
    num=$(((number_of_loops * runs_per_loop) + loop_run_num))
    str="final loop \tloop_run_num: $loop_run_num \trun_num: $num"
    job "$str" &
  done

  wait
  echo -e "\n[$(date)] Finished $total_runs runs"
fi