The Perl Regular Expression (Regex) Pattern Matching Cheat Sheet printable pdf download

The Perl Regular Expression (RegEx) Pattern Matching Cheat Sheet

Concatenation: any sequence of forwardslash delimited characters: /even/ or m/even/

The binding operator (=~) compares a value against a RegEx: $string =~ /odd/

+ means “one or more”, e.g., one or more a's: /ela+/

Parentheses are used to group, e.g., one or more ela's: /(ela)+/

Characters can be escaped with a backslash, e.g., one or more closing parentheses: /ela\)+/

The alternation character is a vertical bar, e.g., 'a' or 'b' or 'c': /a|b|c/

Character classes are an alternation shorthand notation: /[abc]/

Character class ranges are also possible: /[09]/ or /[azAZ]/

Ranges can be inverted, e.g., anything but a vowel: /[^aeiouAEIOU]/

Other shorthand includes a single digit: /\d/, a single space character: /\s/ or a single alphanumeric word

character: /\w/

The \d, \s and \w shorthand can be inverted with \D, \S and \W, respectively

Specific repeatcounts are possible: /\w{2}/ or /\w{2,4}/ or /\w{2,}/

A single element is there “zero or one” time(s): /bart?/

A single element is there “zero, one or more” time(s): /bart*/

Any single character (except newline): /bar./

Word boundaries are matchable: /\beven\b/

The start and end of a string/line: /^hello$/

A blank string/line: /^$/

A string/line of space characters (potentially): /^\s*$/

The binding operator (=~) checks for a match, and can be negated with !~

As well as grouping, the parentheses also remember what was successfully matched in the builtin aftermatch

variables: $1, $2, $3, and so on ...

In Perl, every RegEx is greedy by default – switch off greediness with ?: /(.+?), Bart/

Alternative delimiters (including any bracketing pair) can be specified after the initial “m”: m{http://(.+)}

Substitutions are possible (using the s prefix), as are translations (using the tr prefix) and deletions (using the d

qualifier). Patterns can match globally with the g qualifier and caseinsensitively with the i qualifier

More information on Perl's RegEx technology is in the following manual pages: perlre, perlrequick.

perlretut, as well as the excellent Mastering Regular Expressions, 2

Edition by Jeffrey E. F. Friedl.

The Perl Regular Expression (Regex) Pattern Matching Cheat Sheet