Wicked Cool Shell Scripts

#2 Validating Input: Alphanumeric Only

Users are constantly ignoring directions and entering data that's inconsistent or incorrectly formatted, or that uses incorrect syntax. As a shell script developer, you need to intercept and correct these errors before they become problems.

A typical situation you may encounter in this regard involves filenames or database keys. You prompt the user for a string that's supposed to be made up exclusively of uppercase characters, lowercase characters, and digits. No punctuation, no special characters, no spaces. Did they enter a valid string or not? That's what this script tests.

The Code

 #!/bin/sh # validAlphaNum - Ensures that input consists only of alphabetical # and numeric characters. validAlphaNum() ...