Everything Is a File

On a Linux system, everything is a fileeverything, which may seem obvious at first. Of course a text document is a file, and so is an OpenOffice.org document, and don't forget a picture, an MP3, and a video. Of course!

But what about a directory? It's a file, tooa special kind of file that contains information about other files. Disk drives are really big files. Network connections are files. Even running processes are files. It's all files.

To Linux, a file is just a stream of bits and bytes. Linux doesn't care what those bits and bytes form; instead, the programs running on Linux care. To Linux, a text document and a network connection are both files; it's your text editor that knows how to work with the text document, and your Internet applications that recognize the network connection.

Throughout this book I'm going to refer to files. If it's appropriate, feel free to read that as "files and directories and subdirectories and everything else on the system." In particular, many of the commands I'll cover work equally well on documents and directories, so feel free to try out the examples on both.