Exec::cmd creates zombie processes that are never cleaned up

[scd31]

I found that every time I call Exec::cmd it creates zombie/defunct process that lasts for the lifetime of the program. This can cause problems when spawning many processes.

The workaround was to use Popen instead. It doesn't have the same issue - no defunct processes are created.

[hniksic]

Can you please provide a minimal example of a program that leaves a zombie process?