Example shell script for forking processes in parallell and then waiting for them to finish.

wait_for_bg_process.sh

#!/bin/bash                                                                     

pids=()

# Snooooze for two seconds                                                      
function do_stuff {
    sleep 2
}

# Starts 10 processes                                                           
for i in `seq 10`; do # start 30 jobs in parallel                               
    do_stuff &
    pids+=($!)
done

# When this loop ends, all child processes are finished.                        
for pid in ${pids[@]}; do
    wait $pid
    echo "Finished process with pid: $pid"
done