UNIX for Dummies Questions & Answers

Hi guys!
Im tryin to set up a login script that allows a user to login with only the following "forename.surname" .

The username all contain lowercase letters so thats not a problem to sort out, but im having problems making sure that they can only enter 1 " . " . the code i have so far is this which i thought should work but always comes out as false:

Code:

file=$1

if [ "$file" != '[a-z]\.' ]
then
	echo File must contain a dot!
fi
exit 0

if [ "$file" = '[a-z]\..' ]
then
	echo File must contain no more than 1 dot!
fi
exit 0

Also how do i search the string so that a char can come in any order?
Please help feel so thick!

Try the trusty old case statement.

Code:

case $file in
  *.*.*) echo Many dots;;
  *.*) echo Fine;;
  *) echo No dots;;
esac

The idea to write a shell script to control login sounds rather iffy, though. What happens if somebody types ctrl-C in the middle of your script? (It can be trapped, but there are other more sinister scenarios down that chute.)