Regular Expressions 101

Non-Capturing Group(?:\buser1\b)?

?repeats the group contents below at most once:

\ban ASCII word boundary

user1the literal text user1 (case sensitive)

\ban ASCII word boundary

Group 1(.+?)

.+?any character (except for line terminators), repeated at least once

Non-Capturing Group(?:\buser1\b|$)

1st Alternative\buser1\b

\ban ASCII word boundary

user1the literal text user1 (case sensitive)

\ban ASCII word boundary

2nd Alternative$

$end of line

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

Regular Expression

(?:\buser1\b)?(.+?)(?:\buser1\b|$)

New

I don't get how to create a regular expression that matches everything, except a fixed, single word. Can somebody help me?

Background: alias map for mailserver which redirects all mail to one user. /.*/ -> user1 produces a redirection loop, so i need to exclude user1 from the regexp.

Edit:

The regex should match everything, EXCEPT the single word user1. It should also match input that contains that word, i.e., user11.

Regular Expression

Substitution