Regular Expressions 101

Explanation

Pro

Positive Lookahead(?=^sudo:x:\d+:.*$)

^start of line

sudo:x:the literal text sudo:x: (case sensitive)

\d+a digit, repeated at least once

:the literal : (58₁₀ / 72₈ / 3A₁₆)

.*any character (except for line terminators), repeated any number of times

$end of line

Group 1(.*)

.*any character (except for line terminators), repeated any number of times

:the literal : (58₁₀ / 72₈ / 3A₁₆)

Global pattern flags

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

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

25 tokens

(?=^sudo:x:\d+:.*$)(.*):

New

sudo:x:27:foo,bar,baz
nosudo:x:27:foo,bar,baz

\1<mychar>

sudo:x:27:foo,bar,baz
nosudo:x:27:foo,bar,baz