Hey There,

In bash (and similar shells) you can use read with the -n flag, like:

read -n4

if you want to limit the variable input to 4 characters.

If you want to just trim your variables, you can check the length of a variable by gettings the length value and running a simple if compare. so, if:

var=12345
echo $var = 12345
echo ${#var} = 5

if [ ${#var} -gt 4 ]
then
bail
fi

Hope that helps

, Mike