Regex matching multiple negative lookaheads

Question

I'm trying to match a string (using a Perl regex) only if it doesn't start with "abc:" or "defg:", but I can't seem to find out how. I've tried something like

^(?:(?!abc:)|(?!defg:))

Solution 1

Lookahead (?=foo), (?!foo) and lookbehind (?<=foo), (?<!foo) do not consume any characters.

You can do multiple assertions:

^(?!abc:)(?!defg:)

or:

^(?!defg:)(?!abc:)

...and the order does not make a difference.

Solution 2

Try doing this:

^(?!(?:abc|defg):)

Solution 3

Use this regex:

^(?!abc:|defg:)\s*\w+

This will avoid line start with "abc:" and "defg:" as you want.

Solution 4

… or we could have dropped the alternation from the original expression:

^(?:(?!abc:)(?!defg:))

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Comments

[ysth]

that asks for any string that doesn't start abc: or doesn't start defg:, which is any string

[nhahtdh]

The preceding \b are redundant, and OP doesn't say anything about whatever that follows.