Shell – How to search a wild card name in all subfolders

In bash you can use extglob:

 $ shopt -s extglob  # to enable extglob
 $ cp !(b*) new_dir/

where !(b*) exclude all b* files.

You can later disable extglob with

 $ shopt -u extglob

Try doing this (using bash, brace expansion & globs):

rm -f {a..z}/*.pdf

or

rm -f [a-z]/*.pdf

if your shell lack the brace expansion feature.

Contrary to [a-z], {a..z} (also supported by ksh93) is not a glob, it's brace expansion, it's expanded (before globs) regardless of whether files exist or not. That's like rm -f a/*.pdf b/*.pdf..., regardless of whether a, b... exist or not. Also note that contrary to [a-z] where the range may be locale dependant (like may include é, ś...), {a..z} only works with byte ranges (and reliably only in the ASCII letter ranges, and number ranges)

(Merci Stephane Chazelas for explanations)