Regular Expression Pocket Reference, 2nd Edition

Recipes

Removing leading and trailing whitespace

s/^\s+//
s/\s+$//

Matches: " foo bar “, "foo "

Nonmatches: "foo bar"

Numbers from 0 to 999999

/^\d{1,6}$/

Matches: 42, 678234

Nonmatches: 10,000

Valid HTML Hex code

/^#([a-fA-F0-9]){3}(([a-fA-F0-9]){3})?$/

Matches: #fff, #1a1, #996633

Nonmatches: #ff, FFFFFF

U.S. Social Security number

/^\d{3}-\d{2}-\d{4}$/

Matches: 078-05-1120

Nonmatches: 078051120, 1234-12-12

U.S. zip code

/^\d{5}(-\d{4})?$/

Matches: 94941-3232, 10024

Nonmatches: 949413232

U.S. currency

/^\$\(d{1,3}(\,\d{3})*|\d+)(\.\d{2})?$/

Matches: $20, $15,000.01

Nonmatches: $1.001, $.99

Match date: MM/DD/YYYY HH:MM:SS

/^\d\d\/\d\d\/\d\d\d\d \d\d:\d\d:\d\d$/

Matches: 04/30/1978 20:45:38

Nonmatches: 4/30/1978 20:45:38, 4/30/78

Leading pathname

/^.*\//

Matches: /usr/local/bin/apachectl

Nonmatches: C:\\System\foo.exe

(See MRE 190–192.)

Dotted Quad IP address

/^(\d|[01]?\d\d|2[0-4]\d|25[0-5])\.(\d|[01]?\d\d|2[0-4]\d|25[0-5])\.
(\d|[01]?\d\d|2[0-4]\d|25[0-5])\.(\d|[01]?\d\d|2[0-4]\d|25[0-5])$/

Matches: 127.0.0.1, 224.22.5.110

Nonmatches: 127.1

(See MRE 187–189.)

MAC address

/^([0-9a-fA-F]{2}:){5}[0-9a-fA-F]{2}$/

Matches: 01:23:45:67:89:ab

Nonmatches: 01:23:45, 0123456789ab

Email

/^[0-9a-zA-Z]([-.\w]*[0-9a-zA-Z_+])*@([0-9a-zA-Z][-\w]*
[0-9a-zA-Z]\.)+[a-zA-Z]{2,9}$/

Matches: [e-mail], [e-mail], [e-mail]

Nonmatches: [e-mail], [e-mail], tony@example.a

(See MRE 70.)

HTTP URL

/(https?):\/\/([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})
(:\d{1,4})?([-\w\/#~:.?+=&%@~]*)/

Matches: https://example.com ...