How can a script distinguish a successful command from a failure? *Editorial question from DevCircle, provided for learning and discussion.*

My script should process an input only if it is a regular file. *Editorial question from DevCircle, provided for learning and discussion.*

Parsing the output of ls breaks when filenames include whitespace. *Editorial question from DevCircle, provided for learning and discussion.*

When should a string expand variables and when should it remain literal? *Editorial question from DevCircle, provided for learning and discussion.*

A filename containing spaces breaks when I pass a variable to a command. *Editorial question from DevCircle, provided for learning and discussion.*