Creating a conditional to validate Email addresses

Question

I have used a preg_match based 'regex' in a php script that I use. The regex is ^[\w.-]+@[\w.-]+\.[A-Za-z]{2,6}$

How can I incorporate this in a bash conditional to test Email addresses for basic structure? My email address is in a file called 'email'. (It is looped through as required). Like if [cat email | '/^[\w.-]+@[\w.-]+\.[A-Za-z]{2,6}$/' ]; then { or whatever. I have no idea how to write this. Can anyone help...

Answer 1

Using your regular expression and adapting it to bash to test an address held in the variable email:

#!/bin/bash
if [[ $email =~ ^[[:alnum:]_.-]+@[[:alnum:]_.-]+\.[[:alpha:]]{2,6}$ ]]
then
    echo "Good address"
else
    echo "Bad address"
fi

Notes:

• this uses the [[...]] construct so an ordinary POSIX shell won't do: bash or better is required.

• The =~ operator matches a string, in this case the email address, to a POSIX Extended Regular Expression.

• The actual spec for email addresses, (have a look at RFC5322), is very complex (see this sample but outdated regex) and your regex is only an approximation.