Join multiple complex regex queries with pipe

Question

If I use this regex:

^((?!^aa$).)*$

it works as expected: deselects 'aa' at the line start. But it doesn't if I try to combine it with a similar one:

^((?!^aa$).)*$|^((?!^ss$).)*$

Can anyone explain why, please?

I tried using both regex group kinds, escape slashes the possible ways, google the question a lot, and read many regex docs. But this is too complicated for me yet.

Because `|` it is not a pipe in regex it is just equivalent of boolean OR — Sharofiddin, Dec 13 '22 at 04:48
Ok, a vertical line, OR... but anyway, it combines successfully the regular versions of patterns if they are not as complicated. — Anton Magurski, Dec 13 '22 at 04:52

score 1 · Accepted Answer · answered Dec 14 '22 at 08:04

To disallow aa and ss an alternation inside a lookahead can be used at ^ start.

^(?!aa$|ss$).*

See this demo at regex101 - This will prevent matching any of the defined options.
A lookahead is a zero-length assertion that can be used at a any position in a string.

Join multiple complex regex queries with pipe

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