submitted 4 months ago by TheLugal@lemmy.world to c/commandline@programming.dev

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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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[-] Andy@programming.dev 7 points 4 months ago* (last edited 4 months ago)

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.

[-] TheLugal@lemmy.world 1 points 4 months ago

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

[-] bizdelnick@lemmy.ml 1 points 4 months ago

You don't need parentheses here.

[-] Andy@programming.dev 1 points 4 months ago

~~How dare you?~~

Thanks!

this post was submitted on 15 Feb 2024

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