First let's breakdown the UNIX commands that I will cover into an organized format. Over time - I'll offer more basic UNIX tutorials, but for now this tutorial will cover commands that show system and user information.

There are many more basic UNIX commands that can be put into further categories, but we'll start off slow to ensure we can get a grasp on the essentials.

If you have not done so - you may want to read my quick one page article on how to connect to a remote system via SSH. You'll need to know how to do this in order to connect to your server and follow along with my screenshots.

Commands covered in this unix tutorial : man, who, passwd and finger

Learning more about the software installed on your server is a really good way to get a jumpstart with UNIX. Although the manuals that come with some flavors of UNIX can be quite boring, they are packed with information that even seasoned veterans often overlook.

How to View Manual Pages

Unix Manual pages accompany almost every variation there is. ( I say almost - because I haven't had the opportunity to view or use every variation that exists. I'm not sure anyone has.)

The command : man

Sample Use    : man perl  (show me the perl manual that I have on my machine)

Screenshot of man perl

Using UNIX Who Command

The command : who

Sample Use    : who -T (show me who is connected with the -T switch for more information)

The who command is used to find our which users are currently logged in. By default it should tell you where the connection is made from (IP address), and how long they have been connected to the system.

The command can be useful if you want to find out who is connected and is accepting messages through the system. If you add the command switch -T, you'll get something like the screenshot below. (You won't see the exact same result on your local computer. I issued a man perl command just above our 'who -T' result for the last lesson on the UNIX man command.)

Screenshot of who with -T switch

In the screenshot You'll notice a plus (+) sign next to ttyp0. This means the user is accepting messages. I intentionally blacked out some important details, but from the image above, you can get a general idea of how the command works, and what it is good for.

Using UNIX passwd

The command : passwd

Sample Use    : passwd (no switches this time)

The passwd command is used to alter your password, or your 'authentication token'. On UNIX systems it is always greatly advised to alter your password at least every 6 months. ( every 3 months would be even better)

There are a few neat switches that you should learn, that will make remembering to change your password a breeze. These are standard switches on most variations of UNIX :

-x : Used to set a password lifetime. Note that this can only be used by root.

-w : Used to warn a user that in 'x' number of days their password will expire

There are plenty more switches available, but I think that those two are probably the ones that will help you get started immediately with securing your system.

Screenshot of passwd in use

(As with all of my tutorials that include screenshots, I've taken out any usernames, file names and directories for security purposes.)

finger command under UNIX

The command : finger

Sample Use    : finger -l (show me almost everything about the user that I am logged in as. You can also add a name to view info about another user)

The UNIX finger command shows you alot of useful information about a user. You can find which shell they use, their home directory, and much more.

On my server for example - it comes standard with Bourne Shell. But I also like many of the stock features of other shells. So if you were to issue a finger command on my server for the several different aliases I use, you may find that different users have different shells.

This information can be handy when you need to do some basic level troubleshooting and you have no background on the environment you are working on. That being said - it can also be very dangerous in the wrong hands, so protect your information the best that you can.

Screenshot of UNIX finger in action

Pretty easy stuff so far! In the future, I'll try to add a series of tutorials on commands that control your jobs under UNIX.