mjhjmtu

I was trying to search in man find, and I would like to know what's going on.

$ man find | grep Like
 Like -lname, but the match is case insensitive. This is a GNU
 Like -name, but the match is case insensitive.
 Like -path, but the match is case insensitive.
 Like -regex, but the match is case insensitive.
 Like -name, but the contents of the symbolic link are matched
$ man find | grep "-name"
 find / ! -name "*.c" -print
 find /usr/src -name CVS -prune -o -depth +6 -print
 find /usr/src -name CVS -prune -o -mindepth 7 -print
$ man find | grep "name,"
 and there is no such group name, then gname is treated as a group
 and there is no such user name, then uname is treated as a user

What's going on? How come I can see lines that contain -name, but I don't get those results if I search for -name or name, and why does that show different things? I imagine it has to do with some “metadata” in man page not shown in the terminal, but I don't know.

The default formatting from the man page (such as for bold words) is done by interspersing control characters and letters (and the control characters aren't easily visible in the output).

$ grep 'This is a GNU' /tmp/find.out
 Like -lname, but the match is case insensitive. This is a GNU
$ grep 'This is a GNU' /tmp/find.out | od -c
0000000 L i k
0000020 e - b - l b l n b n a b a m b
0000040 m e b e , b u t t h e m a
0000060 t c h i s c a s e i n s e
0000100 n s i t i v e . T h i s i
0000120 s a G N U n

You can see the backspace/overstrike pairs in the -name word. It looks fine when printed, but means that name isn't a sequence of characters in the output.