|
Previous |
In this lesson you’ll learn about logging in to and out of your UNIX system in addition to some basics of operating your machine. You’ll also learn a bit of the UNIX background, such as why it runs the way it does.
For years UNIX has been a murky topic that has scared away many people. The Internet and World Wide Web were built upon the backs of UNIX machines; therefore, the growing need for Internet connectivity, combined with a desire for increased performance and stability, have caused the number of people interested in using UNIX to skyrocket. At the same time, personal computers are becoming easier to use, and this has spurred the growth of utilities to make the UNIX user’s life easier. Furthermore, this has aided in the push of UNIX—in all its variants—from the server room onto the desktop and into the home.
The first thing you’ll notice when you sit down in front of your UNIX computer is that you need to log in before you can do anything. UNIX is based on a multi-user principle—multiple users can have their own accounts, programs, and settings on the same machine. If you’re familiar with Windows 95/98, multiple users might sound familiar. Windows 95/98 however, does not protect the user’s files from other people; it simply “hides” them. Furthermore, Windows 95/98 does not enable multiple users to run programs simultaneously the way UNIX does.
Ownership and Permissions
UNIX contains the concepts of ownership and permissions. Files are owned by individual users, and permissions control who can view, edit, or run files on the system. Luckily, there is little need for a casual user to worry about ownership. If there is a need to share files with other users on the system, you’ll want to take a look at Lesson 19, “Permissions.” (I'll get the lesson running on soon) After you’ve logged in to your computer, all files that you create during your current session are automatically owned by your account.
Multi-user
In addition to controlling and tracking who owns what, UNIX also enables multiple users to access the system simultaneously. This is a drastic change from the desktop environment offered by traditional personal computer operating systems. For example, while you’re working on a spreadsheet, a coworker might be running a series of calculations for an engineering project. Many different processes can run simultaneously on a single computer by potentially hundreds of different users. Lesson 11, “Processes” explains the concept of processes and how you can manage them.
The login Prompt
In order to log in to your computer, you need to supply a username and password. Your system administrator will most likely provide you with a username and password. Upon entering your information, UNIX loads the appropriate configuration for your account and you can start using the system. The screen that is displayed when you enter your username and password varies from system to system depending on the configuration. There are two possibilities that you might encounter: a graphical login screen or a text-based screen.
Caution:
To Shift or Not to Shift When you’re logging in to—or using other aspects of—UNIX, it’s important to remember that UNIX is case-sensitive. The operating system interprets the capital and lowercase forms of a letter as two different characters. So, if you’ve been given a password that looks like KiWisRgood, you can bet that the machine won’t allow you to log in with kiwisrgood.
Text-based Login
The text-based login screen varies by UNIX distributions. Most text-based UNIX login prompts look like this:
login: password:
When you see the login: prompt, type your username and press return. The password: prompt appears immediately thereafter. When you have successfully typed in both your username and password, you reach a shell prompt. There are a couple of things to keep in mind during your login: Don’t backspace because some systems don’t interpret it properly. Also, when you type your password the data won’t show on the screen (this is to protect your account from prying eyes). Now you’re ready to begin issuing commands to the system. Don’t worry if you don’t know what to do next; you’ll soon learn how to do something productive.
Tip:
What if I Make a Typing Error? Don’t worry if you make a mistake logging in. The system logs the failed attempt to a security file. In the default UNIX configuration, you have another chance to log in, so there’s no need to panic if you don’t get it right the first time—everyone makes mistakes!
Graphical Login
Instead of a text prompt, your machine might be configured with something a bit snazzier—a graphical screen where you can type your login information. This works exactly the same as the text-based system, except it immediately launches you into the X Windows environment. Some of these graphical login screens enable the user to select from various login shells or to perform certain administrative tasks, but all provide the basic utility of logging in to the system. They each have an area for you to enter your username and an area for you to enter your password. Some flavors of UNIX enable you to tab between these fields, whereas other variations require you to position your cursor over each field and click to select the field in which you want to type. In any case, enter your username and password in the obvious locations, and then either hit return or click on the login button.
|
Previous |