I want to pull all of this data into a common format so that I can read it into a spreadsheet. I know Perl is good at text processing, but I don't want to write a whole program. These let you string together a number of smaller commands, which allow you to create very flexible and powerful text processing systems.
Executable programs are files, and so are text files.
Viewing all of these things as files means that even a small program can contain code that allows it to easily read or write information to or from any device or any other file. Redirection is the process of changing the target file descriptor for your program's input, output, or errors. For a simple example of this, let's look at the ls command. Occasionally, things can get a little confusing. There may be times when you'll do something like this and get information displayed to the screen anyway.