How to make grep stop at first match on a line?

Question

Well, I have a file test.txt

#test.txt
odsdsdoddf112 test1_for_grep
dad23392eeedJ test2 for grep
Hello World test
garbage

I want to extract strings which h

Answer 1

As the questioner discovered, this is a bug in versions of GNU grep prior to 2.5.3. The bug allows a caret to match after the end of a previous match, not just at beginning of line.

This bug is still present in other versions of grep, for instance in Mac OS X 10.9.4.

There isn't a universal workaround, but in the some examples, like non-spaces followed by a space, you can often get the desired behavior by leaving off the delimiter. That is, search for '[^ ]*' rather than '[^ ]* '.