Once you log in, you can use the many facilities UNIX provides. As an authorized system user, you have an account that gives you:
A place in the UNIX filesystem where you can store your files.
A username that identifies you and lets you control access to your files and receive messages from other users.
A customizable environment that you can tailor to your preferences.
A file is the unit of storage in UNIX, as in many other systems. A file can hold anything: text (a report you’re writing, a to-do list), a program, digitally encoded pictures or sound, and so on. All of those are just sequences of raw data until they are interpreted by the right program.
In UNIX, files are organized into directories. A directory is actually a special kind of file where the system stores information about other files. A directory can be thought of as a place, so that files are said to be contained in directories and you are said to work inside a directory. (If you’ve used a Macintosh or Microsoft Windows computer, a UNIX directory is a lot like a folder. MS-DOS and UNIX directories are very similar.)
When you log in to UNIX, you’re placed in a directory called your home directory. This home directory, a unique place in the UNIX filesystem, contains the files you use almost every time you log in. In your home directory, you can make your own files. As you’ll see in a minute, you can also store your own directories within your home ...