On Wed, Oct 07, 2015 at 10:44:20PM -0500, Eduardo A. Bustamante López wrote: > > Repeat-By: > > shopt -u extglob > > isnum () ( shopt -s extglob; case "$1" in [1-9]*([0-9])) return 0 ;; > > *) return 1 ;; esac; ) > > Remember that bash parses and interprets the script line-by-line. If you want > to change the parser's operation (for example, have it recognize the extglob > patterns), you have to do it in a different line than where you're using the > special syntax.
Even more: bash parses an entire function all at once. If you want extglob syntax to be permitted inside a function, the extglob option must be turned on BEFORE the function is parsed. You can't flip it inside a function. The normal recommendation is that you should put shopt -s extglob right at the top of your script, directly beneath the shebang. #!/usr/local/bin/bash shopt -s extglob That way extglob is enabled for the entire script, functions and all. I'm not aware of any negative consequences for doing this. In fact, bash has a compile-time option to enable extglob. This isn't the default (yet), but perhaps some day it will be.
