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Learn IT : Software Documentation : Unix-Tutorial | ||||||||||||||||||||||||||||||||||||||||||||||
Unix
OS
UNIX is an operating system. Unlike MacOS and Windows, UNIX is a text-based operating system. Users input commands from a terminal. UNIX allows many people to use the same computer simultaneously. It’s often run on servers, which are powerful computers that allow other computers to contact it for various purposes. Our email and network file storage server, Ada (ada.brynmawr.edu), is a UNIX server. When you login to Ada to change your password or check your email, you are accessing your UNIX account. This document will provide you with some information about UNIX, and the basic commands you need to know to effectively operate in a UNIX environment.
To use a UNIX system, the first thing you must do is establish a connection. We use the SSh protocol to connect to ada. What
is SSh?
When your username and password are accepted by the system, you will see a prompt. For most Ada users, the prompt will be ada> . The prompt is the line where commands are entered. If you were going to change your password, for example, it is at this prompt where you would type the change password command, passwd. Remember that you always need to press Enter (or Return)after entering a command so the system can process it.
There are some advantages to checking your e-mail through our UNIX system. For instance, UNIX programs are text-only, so there is significantly less load time than web-based clients or clients such as Eudora and Thunderbird. Since UNIX systems do not execute attachments, there is no risk of infecting your computer with a virus. Please note that you are logged in directly to the server, anything you move, delete or rename is permanent, so be careful. First, you must select a program to use. We have three mail clients pre-installed for general use on ada.
There are a number of different UNIX command interpreters (called shells). The shell handles your input to the system. Each shell operates in its own unique way. The default shell on Ada is the C shell. To find out what shell you are running, type echo $SHELL at the prompt. If the system responds by printing /usr/bin/shell, where shell is the name of the shell you are using. For example, if the terminal responds with /usr/bin/csh then you are using the C Shell. The C shell is the default shell. Every user has access to all of the shells that are running on ada. In addition to the C shell, we have the Bourne shell (sh), the Korn shell (ksh), bash (bash), and an enhanced C shell (tcsh). To change your shell, simply type the abbreviation of the shell you want at the prompt.
Each shell uses a series of files which store the users preferences. These files are referred to by the system when you log in. Two commonly used files are the .login and the .cshrc. These files can be edited to suit each user’s preferences. Do not edit these files if you are unsure of what you are doing, as you could delete important instructions and thereby lose access to needed paths.
Short for manual, man is the UNIX help system. Often times cryptic, even to seasoned UNIX users, man provides instructions for using every command on the system. Try to use it every once in a while, when you are looking for information about more advanced commands. Your UNIX skills will get better and you’ll actually understand what you’re reading!
"Eeek! My screen just went crazy! A message just popped up out of nowhere!" What is actually happening is that someone (i.e. another user on the system) is sending messages to you using the write command. This command can be used by users to send messages directly to other people who are logged on the same system. To use it, type write username. Type what you like. When you are finished, press the Control and C keys to stop. "But how did so-and-so know that I was on the system?" It’s easy to find out who is logged on the system. You can use the w and who commands to get listings of the users currently on the system. The w command will even tell you what they are doing! If you’re looking for a specific person, you can also finger their account. Finger will also help you find people’s usernames. Simply type f followed by whatever information you know.
Just as you might need to on a Mac or PC, you may need to list, create, and remove files and directories in your UNIX account. Here are some simple commands you’ll need to know:
Creating files in UNIX can be a little tricky. That’s because there are so many ways to do it! Just like there are various word processing programs available for the Mac and the PC, there are many different text editors available in UNIX. You may have already used one of these!
I fingered my friend’s account, and I got all of these neat stuff, like her phone number and quotes. How can I do that?" Very easily! Simply type:
When the pico editor appears, type whatever you wish. Press Control-X to exit and save. Similarly, you can add a one-line project file by typing pico .project and following the above instructions.
From here, you’re on your own, limited only by your courage to try new things! To get you started, here are a few more commands to pique your interest:
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