There are a few questions you need to ask yourself w.r.t. what external call technology to pick (IPC::Open3, system, `STRING`, fork/exec...). What degree of control/sandboxing do you need to have over the process? What kinds of control do you want to have over STDOUT/STDERR? What do you want/need to do with exit codes? I personally almost always use fork and exec, because then I can implement timeouts pretty easily.

Also, since you are working with tar, you may consider using Archive::Tar(CORE module) instead of command-lining it. That might make your error-handling dramatically more straight-forward.