Okay I will let users input spaces as well

I am having a mental block. I have done a couple of searches but havent found anything that I understand (the likes of :alpha: and awk).

Basically I want to give the user an option to enter some text which will go down as a field within a flat file ( which is delimeted by : ).

I want to limit this to 50 characters (I believe I can use typeset -z50 for this)

I also just want a-z,A-Z,(spaces) and numbers. Whats the best way to validate the input?

one way is to use tr to remove unwanted character types. -dc removes everything except those char types you specify. [:alnum;] is alphanumeric, so if you check the length of the string it should be unchanged if it contains only the char types you want.

Jim,

Thanks for the response. Having tested the code thi doesn;t allow me to have spaces within the string. Any ideas?

Also what does the # mean within ${#t}?

Thank you

I am using this code. The tests I have done appear to work.

while true
do
clear
echo "Enter Text: \c"
read t
case $t in
+([a-z]|[A-Z]|[0-9]|[' ']))
echo test string is okay
break
;;
*)
echo test string not okay
sleep 2
;;
esac
done