I've written a script which I want to check for valid input:

dom_option="";
while [ "$dom_option" != [s,r,q,c] ]; do
echo "Choose (s)tart, (r)estart, (q)uit server or (c)ancel."
read dom_option
done

What should I put where I've presently got s,r,q,c so it only accepts one of these values before exiting the loop? Do I have to put four 'or' statements in my comparison?

I know I've read the syntax somewhere, but can't find it...

Dave

If you only want to validate char dom_option you could present it as a case statement:
case "${dom_option}" in
s|r|q|c) continue;;
*) echo "Not a valid option"; exit 1;;
esac

...or you could use a "select" statement to only allow one option of s q r or c:
select action in exit s q r c; do
case "${action}" in
exit) echo "Exiting."; exit 0;;
*) echo "You selected \"${action}\""; break;;
esac
done

Other ways would be to use Bash' getopt or expr. Here's expr:
expr index "${dom_action}" "sqrc" >/dev/null
case "$?" in 1) echo "Not a valid option"; exit 1;; esac

One way to do that:
(This also accepts uppercase answers.)
[edit]
Oops, was already answered by unSpawn while I was typing (too slow).
[/edit]

Thanks, folks, that's been a great help (as always!). Another script ready for users to break...

Does anyone think it's worth having a scripting forum, distinct from a programming forum?

Dave!