Running a limited number of child processes in parallel in bash? [duplicate]

Answer 1

Another option:

PARALLEL_MAX=...
function start_job() {
  while [ $(ps --no-headers -o pid --ppid=$$ | wc -l) -gt $PARALLEL_MAX ]; do
    sleep .1  # Wait for background tasks to complete.                         
  done
  "$@" &
}
start_job some_big_command1
start_job some_big_command2
start_job some_big_command3
start_job some_big_command4
...