Sorry, Karl, I bounced on your post because you made a list and I thought it would be worth to complete the list for the benefit of OP, even though I don't remember having ever used
and qx// is very similar to back ticks. It was not meant as criticizing in any way what you wrote. And thank you for your reference to IPC::Run, I had never come across that module before, and, from a brief look at the documentation, it looks like it might be awfully useful.