Shell globbing isn't universal or portable. So in many cases, it's appropriate to expand globs within the Perl script using File::Glob or other mechanism. For example, in the Microsoft Windows shell (Command Prompt), wildcards are not as powerful or as useful as BSD-style globs; in particular, they can't be used to expand directories (folder), which makes them generally useless for my purposes. I invariably need my Perl scripts to permit their users to glob multiple folder names.