Classnotes | UNIX01 | RecentChanges | Preferences Chances are, if you are in this class you have already had some experience with usernames and passwords under other operating systems. Usernames and passwords are not very different under UNIX-like systems, in fact, it is more accurate to say that other operating systems' username and password authentication schemes are similar to UNIX, as UNIX predates them all.
Before you can use a UNIX system, you must login (this is even true with some special Linuxes such as [Lindows], although in those cases you are automatically logged in). Everything on the UNIX system is started by some user (even the initial boot-up sequence is running as a special init user of some sort depending upon UNIX).
Usernames and passwords under a UNIX system are case sensitive, thus the users "Bob" and "bob" are two different users.
One of the most common problems new UNIX users encounter is incorrect case on password entry! If your password is failing, check to see if CAPSLOCK is enabled!
The administrative user is usually called the "root" user, or the super-user. The root user has administrative access over everything on the UNIX box. This user can start or kill any running program, delete or write to any file on the system, and essentially do anything and everything.
As a result, the root user should be your most protected account. You should pick a password that is very secure for your root account and keep that password very safe. Additionally, you should be careful what programs you run as root, as even the most simple program bug can cause horrendous damage to your system.
It is typically recommended that you only log in as a non-root user, and then change to a root user as needed (this "change" is refered to as "su"-ing or even "sudo"-ing, and will be covered later).
Logging In
There are typically two different ways which you will Login to your UNIX box: Graphical and from the console. In reality, both ways perform the same functions behind the scenes and the difference is only an asthetic one.
Graphical logins can vary from UNIX to UNIX machine, but they all have very common features. Here are a few examples:
