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A little background

Linux first made it's appearance in 1991. Looking at *NIX timeline, like the one here, one can see that many flavors of UNIX already existed, including BSD, Sun OS, HP-UX, and others. Indeed, Linux itself started as an personal offshoot of minix, by Andrew Tanenbaum. If there is something to learn about Linux, as a unique project, it is the story of it's developer, his persona, and the world changes that created a ripe environment for this operating system to flourish.

To me, there are two lesson here: Linux is primarily an active educational pursuit, and is valuable, independent of any other requisits. Also, Linux is as much about people, as it is about computers. Just making software code freely available, doesn't make it better, and it certainly doesn't make people more willing to share with others. Something in this mix of social interaction, and computer science makes Linux successful where many other efforts have not, and I find it important to consider the people behind Linux, while we tackle the technical aspect, as well.

Who Me?

Someone once asked me about my slow goofy laptop, and asked what I did with it. When I mentioned Linux, they were surprised to know I was a programmer, as was I. Until that point, I didn't consider myself one, but after recalling all that I'd learned about using the command line, I realized that I'd been programming my computer, one line at a time. I'd been doing it for a while too, so it didn't really strange to me. So it was, I accidentally became a computer programmer, as will you, with a little bit of practice. I remembered the old addage, that computers only do what we tell them to do, and understood that for Linux users, this was still vary true.

So, we are learning Linux, almost as a second language. It's the way we talk to our computer. The first thing then, is to start a conversation. To speak to the computer, we ask for a login, and a password.It is easy to get the wrong idea about Linux, by simply staring at the prompt you get after login. I have learned that the computer is literally asking you for instruction. It can be a bit difficult to accept the idea of always telling your computer what to do.

This is one of the first bridges to cross with Linux, the desire to communicate patiently, with a machine, to reap the results of successful dialog. So, if you find yourself staring at the prompt blankly, just log out, and consider having some fun elsewhere. Think about what you would like to make your computer do and come back to it when you have a rough idea. Lastly as "housekeeping" note, from here on out, I'll be pretending our computers are in a time machine, and lack all the modern multimedia fanciness, we expect. After all, it's hard to talk to somebody, even a computer, if you are watching a DVD, listening to music, or playing a game. This certainly wouldn't fly in class, and we're definitely in a learning posture.

Command Line on Linux = shell

We are learning to use Linux, using a text interface, or command line. This command line, is used to "talk" to our computer. It allows us navigate through our file system, and get information about files residing on the hard disk. If you have ever used DOS, the Linux command line might not seem so odd. Because of the rich history of UNIX, that Linux largely inherits, it's command line tools are far more formidable than those of DOS, and offer flexibility not often seen in graphical environments.

The command line is also called a "shell". This is because command line interface wraps around the Linux inner-workings like a virtual clam shell, interpreting what you type and passing it to the operating systems internals, in machine-speak, to be executed. the most common shell in Linux is the bash shell. For a more in-depth description and comparison of shells check out this link.

Where am I, what am I looking at?

Though we only learned a few commands, and concepts, they are certainly within the core of utilities one needs to have a practical grip on Linux. First, we learned that upon logging in, we "land" in our own space, located in "/home/", within our file system. This can be verified using the "pwd" command. This command displays our Present Working Directory, and can alway be used to establish your current location. After that we learned how to "survey" our surroundings, by using the "ls" command. This command "lists" the contents of a directory.

For example:

• ls lists the contents your current directory.
• ls -l lists the content of your current directory, with detailed information.
• ls /path/to/other/directory lists the contents of a remote directory, without actually being there.

Where am I going?

We also learned to use the "cd" command. This command allows you to navigate through your file system, and change your location. Like the "ls" program it also has a variety of usage options.

For example:

• cd transports your to your home directory.
• cd /path/to/other/directory transports you to a remote directory.

Connect the Dots

We learned that "." represents your Present Working Directory, and that ".." represents one directory level above your current one. Combining these dot-sequences with "cd" and "ls" will run the commands on the directories the dots represents. As you use the shell more, you'll notice that most Linux utilities can use these dot-sequences.

Bits and Pieces

In an aside, you learned a bit about passwords, and how to change it from the command line. For more information about passwords, check out the following link.

There were a few few things I didn't mention, that would probably be helpful. For instance, when you finish practicing on your shell, you can log out multiple ways. The most obvious one is to type "logout". another way is to hold down the CTRL button, while pressing the "d" key.

For more detailed documentation, here are some sites that offer their own spin on login, and navigation. If you'd like to get a nice used book to get some more info, try "Teach Yourself UNIX in a Week." It's an older text, making easier to find on the secondary (cheaper) market, and it was part of the inspiration for this series.Those of you hungry for more can download this handy PDF of Linux commands, and start tearing it up.

In any case, I look forward to seeing you at our next session. bring your questions, a notepad, and feel free to share the things you've discovered while poking around this new Linux world of yours. If you're still Linux home-less, come by on Wednesday and get an installation done, or ask for a Knoppix CD, so you can practice.

Have fun,

Aaron Estrada

-- AaronEstrada - 29 Aug 2004