Pipe output to two different commands [duplicate]

Question

Possible Duplicate:
osx/linux: pipes into two processes?

Is there a way to pipe the output from one command into the input of two other commands, running them simultaneously?

Something like this:

$ echo 'test' |(cat) |(cat) test test 

The reason I want to do this is that I have a program which receives an FM radio signal from a USB SDR device, and outputs the audio as raw PCM data (like a .wav file but with no header.) Since the signal is not music but POCSAG pager data, I need to pipe it to a decoder program to recover the pager text. However I also want to listen to the signal so I know whether any data is coming in or not. (Otherwise I can't tell if the decoder is broken or there's just no data being broadcast.) So as well as piping the data to the pager decoder, I also need to pipe the same data to the play command.

Currently I only know how to do one - either pipe it to the decoder and read the data in silence, or pipe it to play and hear it without seeing any decoded text.

How can I pipe the same data to both commands, so I can read the text and hear the audio?

I can't use tee as it only writes the duplicated data to a file, but I need to process the data in real-time.

Answer 1

It should be ok if you use both tee and mkfifo.

mkfifo pipe cat pipe | (command 1) & echo 'test' | tee pipe | (command 2) 

Answer 2

Recent bash present >(command) syntax:

echo "Hello world." | tee >(sed 's/^/1st: /')  >(sed 's/^/2nd cmd: /') >/dev/null 

May return:

2nd cmd: Hello world. 1st: Hello world. 

download somefile.ext, save them, compute md5sum and sha1sum:

wget -O - http://somewhere.someland/somepath/somefile.ext |     tee somefile.ext >(md5sum >somefile.md5) | sha1sum >somefile.sha1 

or

wget -O - http://somewhere.someland/somepath/somefile.ext |     tee >(md5sum >somefile.md5) >(sha1sum >somefile.sha1) >somefile.ext 

Old answer

There is a way to do that via unnamed pipe (tested under linux):

 (( echo "hello" |          tee /dev/fd/5 |              sed 's/^/1st occure: /' >/dev/fd/4     ) 5>&1 |     sed 's/^/2nd command: /'  ) 4>&1 

give:

2nd command: hello 1st occure: hello 

This sample will let you download somefile.ext, save them, compute his md5sum and compute his sha1sum:

(( wget -O - http://somewhere.someland/somepath/somefile.ext |     tee /dev/fd/5 |     md5sum >/dev/fd/4   ) 5>&1 |   tee somefile.ext |   sha1sum ) 4>&1