pipeing

The UNIX/Linux philosophy is to have many simple and short programs (or commands) cooperate together to produce quite complex results, rather than have one complex program with many possible options and modes of operation. In order to accomplish this, extensive use of pipes is made.

You can pipe the output of one command or program into another as its input.

In order to do this, we use the vertical-bar, pipe symbol (|), between commands as in:

command1 | command2 | command3

The above represents what we often call a pipeline, and allows Linux to combine the actions of several commands into one.

This is extraordinarily efficient because command2 and command3 do not have to wait for the

previous pipeline commands to complete before they can begin hacking at the data in their input streams; on multiple CPU or core systems, the available computing power is much better utilized and things get done quicker.

Furthermore, there is no need to save output in (temporary) files between the stages in the pipeline, which saves disk space and reduces reading and writing from disk, which is often the slowest bottleneck in getting something done.