Russell Coker wrote: I just meant it has more words. I just meant tr A-Z a-z not tr '[A-Z]' '[a-z]' i.e. you appear to be using tr wrong, but in a way that accidentally doesn't matter. Also your lack of quoting will Do The Wrong Thing if $PWD contains single-letter files in $PWD, e.g. $ curl example.com >a $ echo Hello World | tr [A-Z] [a-z] aello aorld $ curl example.net >b $ git diff --no-index a b $ echo Hello World | tr [A-Z] [a-z] tr: extra operand ‘b’ $ echo Hello World | tr 'A-Z' 'a-z' hello world Now that I'm paying attention, egrep is deprecated (ref. man grep), and you can use -x instead of ^$: LC_CTYPE=C grep -xE '[a-folstq]{4}'