How to Check a Perl Email Address

Check email addresses with regular expressions in Perl.

Perl is a scripting language commonly used on Linux machines and servers to automate common administrative tasks, such as checking an email address given by a user to see if it is valid and fits the email address pattern. To do this, the key is the pattern matching syntax known as "Regular Expressions."

Instructions

1. Open a new text file. You can use any text editor you prefer, from Windows Notepad to a dedicated PERL Integrated Development Environment (IDE), such as EPIC or Padre. However, full scale word processors like Microsoft Word are inappropriate, since they do not, by default, output plain text.

2. Indicate that this is a perl file by pasting the following line at the very top of the text file:

   #!/usr/bin/perl

3. Store an email address in memory:

   $email="myemail\@email.com";

   Notice that the "@" symbol must be escaped (preceeded) with a backslash to let perl know it is part of the text and not code.

4. Compare it to the email test regular expression to see if it fits the pattern of a standard email:

   if ($email =~ m/^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}$/) {

   print "Yes.";

   } else {

   print "No.";

   }

   The "=~" operator tells Perl to compare a string to a regular expression, and the following regular expression dictates that the string must contain a number of letters and digits, followed by an @ sign, followed again by a series of numbers and digits and, finally, at least one extension between two and four characters in size.

5. Save your work with the file name "emailtest.pl." You can run the test by typing "perl emailtest.pl" at a terminal or command line.

Tips & Warnings

• A detailed introduction to Regular Expression syntax is beyond the scope of this article. You can learn more about the syntax for regular expressions using the first resource.

• In Windows, you can get to a command line by clicking "Start" and choosing "Run." Type "cmd." In Mac OS X, you can do it by pressing "Cmd-Spacebar" and typing "terminal."

References

• Regular Expressions: Email

Resources

• Regular Expressions