Bourne scripting - checking user input

Chewy · #1 (**permalink**) 08-16-04, 09:03

Hi all,
As part of a Bourne shell script I'm writing, I need to check the user's input to make sure that it meets requirements (in this case, only alphabetic characters).
The way I'm doing it at the moment is reading the variable, then using a case statement to print an error if the input is incorrect.

Code:

read word
case $word in
       [a-zA-Z]+) echo "Valid" ;;
       *) echo "Error" ;;
esac

I'm guessing that the case statement doesn't support the regular expression [a-zA-Z]+ , any suggestions on other ways I could go about it?
Thanks.

SiverSloth · #2 (**permalink**) 08-16-04, 09:34

Code:

read uname
if [ `expr length $uname` -ne `expr "$uname" : [A-Za-z]` ]
then
  echo "Nasty warning message"
  exit
fi

Damian Ibbotson · #3 (**permalink**) 08-17-04, 04:51

Apply some reverse logic!

case $word in
*[!a-zA-Z]*) echo contains nonalphas;;
*)echo contains alphas only;;
esac

Chewy · #4 (**permalink**) 08-17-04, 08:32

Thanks a lot Damian, seemed to do the trick.

Damian Ibbotson · #5 (**permalink**) 08-17-04, 14:24

Quote:

Originally Posted by Chewy

Thanks a lot Damian, seemed to do the trick.

Chewy,

The problem with your initial attempt was that your expression was a 'regular expression' - the shell is only understands 'file expressions', which are completely different!

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