Command line redirection

There are a couple of useful tips for using the command line:

• The pipe | allows commands to send their output to another, example: ls | grep pdf would only list pdf file in the current directory.
• The tilde `, not to be confused with the single quote ', allows a command to be executed and its output inserted into another, for example: yelp `pwd`/internet.xml would send the complete filename and path to yelp.