Coding 101 24: Perl: Command Line Search and Replace

Hosts: Fr. Robert Ballecer, SJ and Shannon Morse

Guest: Patrick Delahanty

The Code for today’s show is availible at our: Github

Ivory Tower

We learned in the last episode that “Regular Expressions” or “RegEx” is just another way of saying, “find a pattern”
* We learned that we can use RegEx to search a string for that pattern according to a set of parameters and modifiers that WE determine

The usage of RegEx is as Follows:
$nameofstring =~ (Match Operator) / (expression) / (expression) / (Match Expression Operator)

Which means:
$nameofstring =~ (action to take)/(pattern to match)/(pattern to replace match with)/(how to search)

Useful Match Operators
m/ Match Regular Expression
s/ Substitite Regular Expression
tr/ Tranliterate Regular expression

Useful Match Operator Modifiers
g Match globally, find ALL occurences
i case insensitive
m treat string as multiple lines
o Evaluate the expression only once
s treat string as single line
x Use extended regular expressions (Allows you to use white space in the expression)