Find all strings except one string using regex [duplicate]

Answer 1

Judging by you examples, I think you mean "all strings except those containing the word ABC".

Try this:

^(?!.*\bABC\b)

Answer 2

^(?!ABC$).*

matches all strings except ABC.

Answer 3

Invert the Match with GNU Grep

You can simply invert the match using word boundaries and the specific string you want to reject. For example:

$ egrep --invert-match '\bABC\b' /tmp/corpus 
"A"     --> Match
"F"     --> Match
"AABC"  --> Match
"ABCC"  --> Match
"CBA"   --> Match

This works perfectly on your provided corpus. Your mileage may vary for other (or more complicated) use cases.