[SOLVED] sed search result identical to searching for its opposite

Question

In sed, I want to detect lines that are NOT terminated by any of the sentence terminators, '.?!', with possibly a following quote sign, and to join such lines with their following line.
Here is a file of data, y
man, why not Great-grandfather?"
I've never
And here are the results of two opposite sed commands run on that data.  Why are the results identical?
~ $ sed '/[^.?!]["]*$/{N;s/\n\t/ /}' y
man, why not Great-grandfather?" I've never
~ $ sed '/[.?!]["]*$/{N;s/\n\t/ /}' y
man, why not Great-grandfather?" I've never
~ $
I use a similar regex, [^.?!], in a substitute where it performs as expected, why should it be different in a search?
Last edited by porphyry5 (2014-11-30 23:56:25)

Answer 1

Trilby wrote:
$ sed '/[.?!]"*..$/{N;s/\n\t/ /}' y
man, why not Great-grandfather?" I've never
$ sed '/[^.?!]"*../{N;s/\n\t/ /}' y
man, why not Great-grandfather?"
I've never
EDIT: okay I've edited this a few times.  I had it working, but I couldn't figure out why.  Now I have: the line matching needs the apparently needs the newline and tab two unknown characters before the $.
D'Oh, I think I just figured it out: It matches correctly, but in the non-matching case the quote is still optional and the expression matches *any* character other than the punctuation, which includes the quote.  So the line matches both cases.  Here's what you probably want:
$ sed '/[.?!]"*$/{N;s/\n\t/ /}' y
man, why not Great-grandfather?" I've never
$ sed '/[^.?!"]$/{N;s/\n\t/ /}' y
man, why not Great-grandfather?"
I've never
OK, I just tried it thus
sed '/[^.?!]["]*.$/{N;s/\n\t/ /}' y
which works for me, but I'm not understanding what is going on (I'm keeping the ["] because in the real version within a script it is ["'] but I can't get a ' to be acceptable within this command line test).  The ? is there, the " is there, so what is the . immediately before the $ matching to?
This works too
sed '/[^.?!"]\+$/{N;s/\n\t/ /}' y
, which I think I will go with as it conforms to the actual data patterns its likely to find.  The form without the \+ is just matching to the " and not to the ?.  I prefer to have it match to both if they are there, and the sentence terminator must always be there.  I haven't used sed very much before, it certainly seems to have its own slant on things.  I thank you very much for your help.