parexec

Usage: parexec NUMTHREADS
where NUMTHREADS is the number of commands you want to execute in parallel

The commands are read from stdin. Empty lines are ignored. Lines containing a single `-' instruct parexec to wait until all previous commands have finished before starting to execute further commands.

When sending a SIGINT to parexec (usually done when you hit CTRL-C) it will wait for currently running processes, but if they are done parexec will exit ignoring all the following commands.
When sending a SIGQUIT to parexec (usually done when you hit CTRL-\) or by sending SIGTERM to parexec (e.g. with kill parexec_pid) it will terminate the running processes immediately and exit.

After the start of parexec your shell window will be split up horizontally into NUMTHREADS sections. Each section containing the output of one command (which will scroll away as your command writes too much) and a status bar.