how do you pipe output from one command to another?

something like

which mplayer | rpm -qf

I am trying to find out which rpm mplayer belogns to.....but it doesn't work
neither does

which mplayer | rpm -qf -

help.....

you can rpm -qa|grep mplayer

or

rpm -qf $(which mplayer)

if that's what u meant in ur post.

Well I know this will work in this case. But I meant it as an example of how to use pipes to chain multiple commands. How do you do it in general though??

screwed up

You mean something like this?

<command> | <another command> ; <then do this command> | <yet another command>

or

<command> | <2nd command> | <3rd command> | <4th command>

A good article about it: Linux and the Tools Philosophy

Or do you mean:
<command> | <take output from last command as input for this command> output

Cool

that rpm -qa|grep mplayer
is a pipe. rpm -qa lists all the packages installed.
here all that text is piped into grep which searches
it for the word mplayer, then when mplayer is found,
grep prints the line that it was found on.

in general a program that can send a stream of
text or bytes is sent to the input of another program
that does something to that data.

tar clfv - .|(cd /mnt/copy; tar xpf -)

another example to look at

Try this :

rpm -q -a | grep mplayer

seeing as everyone else said exactly the same thing, i might as well

rpm -qa | grep mplayer

it's also wrong... but nevermind. actually answering the question though, a program can only be used with a pipe if that is how it is written. while it could be designed for rpm to accept a file name through a pipe it is not particuarly useful, and so presumably no one bothered implementing it. personally in your example i would have said

rpm -qf `which mplayer`

but obviously that was only used as an example. you've got the right idea, it just isn't possible in that example.