The =~ operator 

• Pattern matching can also be used to manipulate variables. In particular, many CGI scripts take advantage of the "=~" operator in conjunction with the substitution operator using the format 

$variable_name =~
s/[string_to_remove]/[string_to_add]/gi; 

• For example, if we want to censor every occurrence of the word "Frack" from the client-defined input field "comment", we might use the line 

$form_data{'comments'} =~ s/frack/censored/gi; 

Additional Resources:

• Perl 
• Perl Resources 

String Modifiers
Table of Contents
Using the split and join functions