Discarding output

Sometimes you don't need to redirect output to anywhere; you just want to throw it away and get rid of it. In this case, you can redirect the output to /dev/null. This is often used with error messages. For example:

elliot@ubuntu-linux:~$ cat planets.txt blabla 2> /dev/null 
Saturn is a planet.
Mars is a planet.
Venus is a planet.

This will redirect the error message to /dev/null. You can think of /dev/null as a garbage collector.