[ale] Q: Bash: test for existence of any file matching a glob pattern.

[jknapka at kneuro.net (Joe Knapka)]

Christopher Bergeron <christopher at bergeron.com> writes:

> Joe, are you looking for .h files in the current directory or system
> wide?   If you're just looking for the current directory, try this:
> 
> for f in `\ls *.h`; do echo "doing something to $f; done

This has the same trouble as "for f in *.h" -- it works great
when there *are* files matching the pattern, but it does the
wrong thing when there aren't any.

The answer turns out to be, "set the nullglob shell option,
eg shopt -s nullglob". That changes the behavior of glob
expansion: when nullglob is set, "*.h" always expands to
precisely a list of existing .h files in the current directory
(that is, if there aren't any files matching the pattern,
it expands to "" rather than "*.h").

Doubtless this will come back to bite me in some soft-tissue
area in the future, but for now, it works.

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