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verifing input from bash read

Hello,

I have a simple shell script that read input from a user. The input is only a number or single letter. What would be the best way to verify the input or remove any harmful characters ?

I was thinking about using:

--snip--
read inputvariable
echo ${inputvariable} | grep -E '^[[:alnum:]]{1,2}$' > /dev/null

if [ $? -eq 0 ]; then
continue because the input is only 1-2 digits and is either a number or letter
else
exit 1
fi
--snip--

Is that enough though ??

Michael.

you could use case.

you can use single characters or wildcards.
the *) at the end is like the default

So if there are no matches it falls through to the end.

e.g:

Code:



echo input  y or number or grockle_bum grockle_leg

while read x; do



    case $x in



        [yYNn]) echo ok

            ;;



        [0-9]|[0-9][0-9]) echo number

              ;;



          groc*)

              echo ooh a grockle!

              ;;

            *)

            echo doh

            break 2

            ;;

        esac

echo input  y or n or grockle_bum grockle_leg

        done

~

man bash
also look at the select statement maybe
try

Code:

select file in *;do cksum $file;done