Batch Parallel cURL Download in Bash

batch-parallel-curl-download.sh

#!/usr/bin/env bash

waitFor() {
  pids=$1
  errs=()

  for pid in ${pids[@]}; do
    echo "wait $pid"
    wait $pid
    errs+=($?)
  done

  for err in ${errs[@]}; do
    echo "$err"
  done
}

pids=()
curl "http://urlecho.appspot.com/echo?body=1111%0A" & pids+=($!)
curl "http://urlecho.appspot.com/echo?body=2222%0A" $(sleep 2) & pids+=($!)
curl "http://urlecho.appspot.com/echo?body=3333%0A" $(sleep 3) & pids+=($!)
curl "http://urlecho.appspot.com/echo?body=4444%0A" & pids+=($!)
curl "http://urlecho.appspot.com/echo?body=5555%0A" $(sleep 5) & pids+=($!)
curl "http://urlecho.appspot.com/echo?body=6666%0A" & pids+=($!)
waitFor $pids

pids=()

curl "http://urlecho.appspot.com/echo?body=1111%0A" &
pids+=($!)

curl "http://urlecho.appspot.com/echo?body=2222%0A" $(sleep 2) &
pids+=($!)

curl "http://urlecho.appspot.com/echo?body=3333%0A" $(sleep 3) &
pids+=($!)

curl "http://urlecho.appspot.com/echo?body=4444%0A" &
pids+=($!)

curl "http://urlecho.appspot.com/echo?body=5555%0A" $(sleep 5) &
pids+=($!)

curl "http://urlecho.appspot.com/echo?body=6666%0A" &
pids+=($!)

waitFor $pids