Why is egrep only printing the last match when I egrep the `man egrep` file?

Question

Okay, so when I check the man egrep output, I see the word recur appear in many places.

One of those places is in the "--recursive" part of the man egrep file.

But, why doesn't it get found when I search the egrep output?

The following does not catch the "--recursive" part of the man egrep file:

man grep | grep -i "recur"

But why not?

are the --recursive entries boldened? Then there may be additional characters interposed. Seems to me that grep -i "re" does find the lines you look for. — djna, Sep 19 '16 at 21:46
It works for me. I guess my version of `man` doesn't produce all the formatting when the output is piped. — Barmar, Sep 19 '16 at 21:59
@Barmar, ...by contrast, OS X's does format even when stdout is not to a TTY. It'd probably be helpful if the OP specified their platform. — Charles Duffy, Sep 19 '16 at 22:01
Yeah, I just tried it on Linux and OS X, with different results. Probably a GNU vs. BSD issue. — Barmar, Sep 19 '16 at 22:02

score 1 · Answer 1 · answered Sep 19 '16 at 21:49

1

Pipe to od -c to see that bold words are emboldened two letters at a time

man grep | od -c

\b   g   r  \b   r   e  \b   e   p  \b

the lines you miss are bold.

answered Sep 19 '16 at 21:49

djna

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score 0 · Answer 2 · answered Sep 19 '16 at 21:48

Even though you are seeing many places where the token "recur" occurs, what you are not seeing are the control characters hidden between the characters - r, e, c, u, r. The control chars are being interpreted by your shell. In reality, in the entire man page, there are only a few places where those 5 chars appear continuously without any control (hidden) characters between them.

Try this:

man grep > text.out
vim text.out

Find the line that you are talking about. You will see the control characters being shown by vim.

Why is egrep only printing the last match when I egrep the `man egrep` file?

2 Answers2