Cat is useless in that line:

   $ grep " 80/tcp" /etc/services 
   http            80/tcp          www www-http    # WorldWideWeb HTTP

http://partmaps.org/era/unix/award.html#cat

It's not useless. With cat, I don't have to remember the order of grep's arguments.

Interesting. With grep you need at least something to search (one argument), don't you? If you don't provide another argument to say "where", it reads from standard input (as most unix commands).

But you already know that because you're using it that way with cat. How can you don't remember then the order of the arguments?

There:

> {1} With grep you need at least something to search (one argument), don't you? {2} If you don't provide another argument to say "where", it reads from standard input (as most unix commands).

And ‘find’ is the other way around.

I just don't see any reason to not to use cat. It's not like grep will use fseek() to speed anything up, if I call it with file URI instead.

I too would cat the file first, just get in the habit of doing it.