In the "Usage" document on grep at http://www.gnu.org/software/grep/doc/grep_13.html#SEC13
I'm not sure about this section: > 13. Why are my expressions whith the vertical bar fail? > > > /bin/echo "ba" | egrep '(a)\1|(b)\1' > > The first alternate branch fails then the first group was not in the > match this will make the second alternate branch fails. For example, > "aaba" will match, the first group participate in the match and can be > reuse in the second branch. I am assuming the headline was supposed to be: "Why are my expressions WITH the vertical bar FAILING?" I am not clear at all what the explanation is trying to say. Maybe I just need to brush up on my regular expressions. I do suspect that "fails" should be "fail" and "reuse" should be "reused". Thanks -Scott
