If you want the STDOUT and STDERR, plus the ability to write to STDIN , use something like IPC::Open2 or IPC::Open3.

If you need to share data from the executable in realtime, with other parts of the script, threads might be useful.

If you just need to run the executable without collecting returns from it, just use backticks, simple piped opens, etc.

Finally, I see that many of your previous questions were Tk related, and in that regard, you must take precautions to NOT block the functioning of the Tk eventloop with your program execution. So with Tk, or most any gui, piped opens or IPC::Open3, or threads are used, to run the external command in a different time slice.