DOI link for Regular Expressions
Regular Expressions book
A common feature of every scripting language is support of regular expression (REGEX in programming jargon). What are regular expressions? They are expressions that sumarize a text pattern. A known case of regular expression is the abreviations used in most operating systems, like using “ls *.py” (or “dir *.py”) to list all files ended in “.py”. These are known as wildchars.