I'd like a regex to match thank-you but exclude it when the string contains the word removals. So contact-thank-you should return a positive but removals/contact-thank-you should return a negative
I don't know much about regex and found a couple of posts refering to negative lookaheads. The best i could come up with was
(?!(?:removals)).*thank-you
which is clearly rubbish. Could anyone help?
Thanks
What you ideally want in this case is a negative lookbehind, since you're looking "behind" (to the left) of the word you're matching to make sure something's not there.
A complication here is that many regex engines don't permit variable-width negative-lookbehinds.
But if you can anchor to the start of the string you want to match somehow, then you can use lookahead from that anchor, instead.
(?:\s|^)((?!removals)\S)+thank-you(?:\s|$)
bananas/fred-thank-you - MATCH.
bananas/fred-no-thank-you - MATCH.
bananas/thank-you-with-words-after - no match.
removals/fred-thank-you - no match.
non-removals/fred-thank-you - no match.
bananas/removals-thank-you - no match.
bananas/thank-you-supremovalsale - no match.
bananas/fred-sorry - no match.
I am presuming that the characters permitted in the string are "anything but whitespace".
So it starts out by looking for either the beginning of the string, or some whitespace; then any number of non-whitespace \S characters that aren't the beginning of the string "removals"; then the string "thank-you".
But I suspect what you're actually looking for is something a little different, maybe something like:
^(?!removals\/)\w+\/[-\w]*thank-you$
bananas/fred-thank-you - MATCH.
bananas/fred-no-thank-you - MATCH.
bananas/thank-you-with-words-after - no match.
removals/fred-thank-you - no match.
non-removals/fred-thank-you - MATCH.
bananas/removals-thank-you - MATCH.
bananas/thank-you-supremovalsale - no match.
bananas/fred-sorry - no match.
This assumes that the structure is very fixed: to include anything that ends "/blah-blah-thank-you", unless the first word is exactly "removals/". Without knowing the exact specification, though, the first seems the most likely to be helpful.
If you're not trying to extract this string from many others, but are just checking a URL to see if it matches this pattern, then you can simplify it a lot:
^(?!.*removals).*thank-you
bananas/fred-thank-you - MATCH.
bananas/fred-no-thank-you - MATCH.
bananas/thank-you-with-words-after - MATCH.
removals/fred-thank-you - no match.
non-removals/fred-thank-you - no match.
bananas/removals-thank-you - no match.
bananas/thank-you-supremovalsale - no match.
bananas/fred-sorry - no match.
This just matches any string that has "thank-you", and not "removals".
^(?!.*removals).*thank-you.*. It depends on what the environment is, if you need the whole string match or not. Please show your code to help you better and quicker. Are the strings multiline, BTW?.in most regex flavors does not match line break characters.string.containslike methods.grepthen you can do:grep 'thank-you' <file> | grep -v removals