In Linux, you can use a pipe to send the output of one command to be the input (argument) of another command:
A pipe is represented by the vertical bar character on your keyboard. Linux pipes are very useful as they allow you to accomplish a relatively complex task in an easy way, and throughout the book, you will see that they come in handy very often.
Before we do an example, let's first rename the hard.txt file to facts.txt, as we removed the facts.txt file back in Chapter 6, Hard vs. Soft Links:
elliot@ubuntu-linux:~$ mv hard.txt facts.txt
Now let's use the head command to view the first five lines of facts.txt:
elliot@ubuntu-linux:~$ head -n 5 facts.txt
Apples are red.
Grapes are green.
Bananas are yellow.
Cherries are red.
Sky is high.
Now I want to display only the fifth line Sky is high. of the file facts.txt; how can I do that?
That's where the power of Linux pipes comes into play. If you pipe the output of the previous command...