If you want to read and write from/to external program you need some IPC (see perlipc and notably this part) as offered by IPC::Open2 IPC::Open3 ( both CORE modules and Open3 to also have STDERR but pay attention to different order in respect to Open2 flavour) or some CPAN module as IPC::Run IPC::Run3

There are others but the above are more often used, i think. See also portability / system / elegance and Re: open2() in Windows

L*

update ah! bravo NetWallah below, i was trying to remember the name of that module with no luck. See also Capture::Tiny