In what format does piped output get sent and received from one command/program to another? When a command is piped to another command in what way or in what format does the piped output exist/get sent? Is it a temporary file? Is it a string? And how does the command that receives the piped output decode/read that output? * * * _Example:_ echo "Someone string" | ./program | tail * * * Does the program "`program`" receive the output of `echo` as a file? How would the program read in that input?

It goes as a bit stream. That's how it's sent and how it's received. The interfaces are _file descriptors_ (or _handles_ ). A simple file is also handled that way.

See:

* Standard streams on Wikipedia
* File descriptor on Wikipedia