All we've been discussing in this section is redirecting output command to another file; what about redirecting output from one command to another? Well that's exactly what the next section is for.
Pipes are interprocess communication mechanisms, which are mechanisms that allow processes to communicate with one another, in operating systems that allow output from one process to be funneled from to another process as input. In other words, you can turn the standard output of one program into the standard input of another.
In fact, many pipes work exactly this way by duplicating file descriptor 0 for one process and allowing another process to write to it.
The following command shows how to use a pipe in bash speak:
[command line] | ...