regex101: Python Match Workspace

Group 1((?:[a-z][a-z0-9-]*[a-z0-9]\.|[a-z]\.)(?<!\bwww\.) (?:[a-z][a-z0-9-]*[a-z0-9]\.|[a-z]\.)* (?:[a-z][a-z0-9-]*[a-z0-9]|[a-z]))

Non-Capturing Group(?:[a-z][a-z0-9-]*[a-z0-9]\.|[a-z]\.)

1st Alternative[a-z][a-z0-9-]*[a-z0-9]\.

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

Character Class[a-z0-9-]*

*matches any number of characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[a-z0-9]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

2nd Alternative[a-z]\.

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Negative Lookbehind(?<!\bwww\.)

\ba Unicode word boundary

wwwthe literal text www (case insensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:[a-z][a-z0-9-]*[a-z0-9]\.|[a-z]\.)*

*repeats the group contents below any number of times:

1st Alternative[a-z][a-z0-9-]*[a-z0-9]\.

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

Character Class[a-z0-9-]*

*matches any number of characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[a-z0-9]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

2nd Alternative[a-z]\.

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:[a-z][a-z0-9-]*[a-z0-9]|[a-z])

1st Alternative[a-z][a-z0-9-]*[a-z0-9]

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

Character Class[a-z0-9-]*

*matches any number of characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[a-z0-9]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

2nd Alternative[a-z]

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

Search reference

Regular Expression

((?:[a-z][a-z0-9-]*[a-z0-9]\.|[a-z]\.)(?<!\bwww\.)
 (?:[a-z][a-z0-9-]*[a-z0-9]\.|[a-z]\.)*
 (?:[a-z][a-z0-9-]*[a-z0-9]|[a-z]))

New

0.example.com
www.www.example.com
dash-dash.example.com
-dash.example.com
dash-.example.com
some.something.com
www.helloworld.com
apple.www.example.com
example-2.com
awww.example.com
TV.S1E01.mp4

Regular Expressions 101

Regular Expression

Substitution