I heard about "useless use of cat" and found some suggestions, but the following outputs nothing in my bash shell.
Using cat works as expected though.
I'm using Fedora Core 18 and GNU bash, version 4.2.45(1).
EDIT: Using it in front of a pipe doesn't work either.
< filename | grep pattern
Whereas using cat works as expected.
cat filename | grep pattern
EDIT2: To clarify, I know that I can use this
grep pattern < filename
but I read here http://stackoverflow.com/questions/11710552/useless-use-of-cat that I can also use it in front of the command. It does not work in front of the command though.