globs vs regexps

globs vs regexps

The "failglob" option will probably be of interest to many users. When set, this option will cause an error when a regular expression fails to match any files

Filename globs are not regular expressions.

Filename globs are those expressions where ? matches a single character, * matches any number of characters, and the beginning and end are always anchored (e.g. a*d matches abcd but not qabcdz).

Regular expressions have a precise meaning I don't remember at the moment, but commonly refer to expressions where a period matches a single character, a * modifies a previous bit of the expression to match any number of that bit, and beginning and end achors must be explicitly specified if they are desired. (a.*d matches both abcd and qabcdz.)

The single-star glob "*" is equivalent to the four-character regular expression "^.*$".

Confusion between these two systems trips up a lot of people, so it's important not to refer to one when you mean the other.

Note: you can avoid this step in the future by logging into your LWN account.