In a bash script, how do I sanitize user input?

Question

I\'m looking for the best way to take a simple input:

echo -n \"Enter a string here: \"
read -e STRING

and clean it up by removing non-alph

Answer 1

Bash can do this all on it's own, thank you very much. If you look at the section of the man page on Parameter Expansion, you'll see that that bash has built-in substitutions, substring, trim, rtrim, etc.

To eliminate all non-alphanumeric characters, do

CLEANSTRING=${STRING//[^a-zA-Z0-9]/}

That's Occam's razor. No need to launch another process.