this post was submitted on 15 Feb 2024
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Inverting match with grep, unless another term exists (self.commandline)
submitted 9 months ago by TheLugal to c/[email protected]
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I have a list containing a set of tags, and would like to exclude one tag, unless another tag exists in the line.

Say I have the following list, and want to exclude B, unless A is present.

[A,B]
[A,C]
[B,C]
[A]
[B]

I can reverse grep for B:

> grep --invert-match "B"
[A,C]
[A]

How can I find the previous list, but also the item containing [A,B]?

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[โ€“] [email protected] 7 points 9 months ago* (last edited 9 months ago) (3 children) 
grep -E '(^[^B]*$|A)'

EDIT: Whoops, I meant to make this a top-level comment.

EDIT 2: On one client it looked like a nested comment and on this other client it looks top level and now I'm a confused old man.

[โ€“] TheLugal 1 points 9 months ago

Haha, on Lemmy.World it looks like a top level. Thank you, either way :)

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