No, we're not going to start talking about plumbing here. In Linux, ``pipes'' connect the standard output of one command to the standard input of another command.
Let's take a step back, to the ls command. There are plenty of options available with ls, but what if the contents of a directory stream by too quickly for you to view them?
Let's view the contents of the /etc directory.
ls -al /etc
How do we take a closer look at the output before it races off the screen?
One answer is to pipe the output to a utility called less. Known as a
pager, less, (like more) allows us to view information one page
(or screen) at a time.
We use the vertical bar (|) to pipe the commands (as shown in Figure
34).
Now we can view the contents one screen at a time. To move forward a
screen, just press [Space]; to move back a screen, press [B]; to
quit, just press [Q].
Actually, we've already been using pipes, before we even discussed what
they were.
In previous references to man pages, we used the following to print out the
man page entry:
Here, we're sending the output of man ls to a filter called col
with an option of -b to help format the text for the printer, then we
sent the output of that to the printer using the lpr command.
ls -al /etc | less
man ls | col -b | lpr