In the Beginning…

In the beginning, there was no graphical interface. We had to type all of our commands while walking to school in the snow, uphill both ways. These days, we have pretty flashy interfaces that do everything for us. Still, someday the need will arise, and you will have to learn how to use the command line.

Don’t worry! It’s actually pretty easy, and the only truly efficient way to do certain things. You might even come prefer it (we have kool-aid).

There are a bunch of different command line interfaces out there, but you’ll probably only end up using the bash (bourne again shell). We’re just going to teach you the bare essentials, which are pretty consistant for all shell types.

Basic Commands

Display Current Directory

pwd

Once you’ve opened up the terminal, you’re just stuck there, adrift in your home directory. You probably want to know where you are. pwd, short for present working directory, does just that. It tells you where you are.

Listing Contents of a Directory

ls

This will probably be your most used command. ls lists all of the files in the current directory (or in a different directory if listed after the ls).

Change Directory

cd [directory path]
cd .. (goes up one level)
cd ~ (goes to your home directory)

Now, you probably want to know how to change directories. The cd command will handle that. Give it the directory that you want to switch to.

Copy and Move Files

cp [file] [new location/file name]
mv [file] [new location/file name]

These are pretty straightforward. cp copies files to whichever location you want them. The copy can have a different name. mv moves files, and can be used to rename them.

Delete Files

rm [file name]
rmdir [directory name]

As you can probably guess, rm is used to remove files. rmdir is used to remove directories. By default, a directory cannotnt be deleted unless it is empty. To bypass that, use rm -rf [directory name]

Make Directories

mkdir [directory name]

Want to make a new directory for your files? Just use mkdir.

Print contents of files

echo [string]
cat [filename]
cat [filename] | less (displays the text of a file a few lines at a time)

echo and cat are both used to print text to the string. echo is commonly used to print strings of text or the value of system variables. cat is often used to display the text of files.

Find Files and Directories

find [filename]
locate [filename]

The find command will hunt down any file on your system and tell you where it is. Nothing is safe.

Look up Commands

apropos [keyword]

The final basic command that we’ll teach you is the apropos command. apropos is a search tool that can be used to find any command related to your keyword. For instance, apropos browser would find things like firefox.

Running Your Programs

Java

javac [filename.java]
java [filename]

To run your Java programs, you must first compile them with javac. This creates an executable .class file, which can be run with java followed by the filename.

C/C++

gcc [filename.c] -o [executable name]
g++ [filename.c] -o [executable name]
./[executable name]

To compile your program, first use the appropriate compiler. gcc for C language files and g++ for C++ programs. After that, you can run your executable.

Don’t Be Afraid

Take a deep breath. I understand, you’re used to Windows. This is a brave new world for you. The good news? Linux is easier than ever to use. Forget what you’ve heard. Linux isn’t just for the hardcore. In fact, a few things are even easier to use in Linux than in other operating systems.

Just sit back and keep reading. We’ll explain a few of the key differences between operating systems and help ease your transition into the open-source world.

What is Linux?

Before we really get started, you may want to know exactly what Linux is and a little of its backstory. Like many of these stories, it all began with MIT and AT&T Bell Labs. Back in the 60s, they developed an operating system called Multics. Multics kind of sucked, and a couple of guys at Bell Labs began working on a new operating system called Unix.

However, there was still a big problem with Unix. It wasn’t free. In 1984, Richard Stallman began the GNU project with the intention of creating a variant of Unix made entirely of open-source software. They did piece together an incredible collection of utilities, but they lacked the most important component - the kernal. The kernal is the very heart of the operating system. It is the control point, the brain. An operating system cannot operate without a kernal.

In 1991, Linus Torvalds, a student at the University of Helsinki, decided to write his own operating system. He used the Unix-based Minux as his starting point. From there, he developed his own kernal, which he named Linux. The GNU Project had found its kernal.

These days, there are dozens upon dozens of “Linux” operating systems. Which ones are Linux? Why isn’t there one Linux? This is a slightly confusing topic to any Linux newbie, which is pretty understandable. Linux is actually just the kernal portion of the operating system. Technically, any operating system using that kernal can call itself Linux. All Windows operating systems have kernals, too. The recent editions of Windows use the Windows NT kernal. So, the short answer is that all of these operating systems are “Linux.” They all also have their own features and uses. LOUD (the CSEE maintained version of Linux) is based on the Ubuntu Linux operating system.

Ubuntu is based on the Debian Linux operating system. Ubuntu has placed its focus on making Linux easy to use for anyone. Ubuntu is also notable for its stable release schedule. New releases are made every six months according to a strict schedule.

Getting Ubuntu

If you’re a student in the CS department, you already have access to Ubuntu. LOUD, a special variant, is installed on every lab machine. Go to the Helpdesk office in 701 ESB and ask for a copy.

You can download a copy of Ubuntu or request free CDs from here.

Important System Locations

We thought you might want to know where some of your files are. Here is a handy diagram of the Unix/Linux file hierarchy. Your own files will most reside in /home/[username]. This could be thought of as being similar to “My Documents” in Windows. Most executable programs will reside in /usr/bin.

(Reprinted from: http://www.comptechdoc.org/os/linux/usersguide/linux_ugfilestruct.html)

/ - Root
|—root - The home directory for the root user
|—home - Contains the user’s home directories
| |—-ftp - Users include many services as listed here
| |—-httpd
| |—-samba
| |—-user1
| |—-user2
|—bin - Commands needed during bootup that might be needed by normal users
|—sbin - Like bin but commands are not intended for normal users. Commands run by LINUX.
|—proc - This filesystem is not on a disk. Exists in the kernels imagination (virtual). This directory
| | - Holds information about kernel parameters and system configuration.
| |—-1 - A directory with info about process number 1. Each process
| has a directory below proc.
|—usr - Contains all commands, libraries, man pages, games and static files for normal
| | operation.
| |—-bin - Almost all user commands. some commands are in /bin or /usr/local/bin.
| |—-sbin - System admin commands not needed on the root filesystem. e.g., most server
| | programs.
| |—-include - Header files for the C programming language. Should be below /user/lib for
| | consistency.
| |—-lib - Unchanging data files for programs and subsystems
| |—-local - The place for locally installed software and other files.
| |—-man - Manual pages
| |—-info - Info documents
| |—-doc - Documentation for various packages
| |—-tmp
| |—-X11R6 - The X windows system files. There is a directory similar to usr below this
| | directory.
| |—-X386 - Like X11R6 but for X11 release 5
|—boot - Files used by the bootstrap loader, LILO. Kernel images are often kept here.
|—lib - Shared libraries needed by the programs on the root filesystem
| |—-modules - Loadable kernel modules, especially those needed to boot the system after
| disasters.
|—dev - Device files for devices such as disk drives, serial ports, etc.
|—etc - Configuration files specific to the machine.
| |—-skel - When a home directory is created it is initialized with files from this directory
| |—-sysconfig - Files that configure the linux system for networking, keyboard, time, and more.
|—var - Contains files that change for mail, news, printers log files, man pages, temp files
| |—-file
| |—-lib - Files that change while the system is running normally
| |—-local - Variable data for programs installed in /usr/local.
| |—-lock - Lock files. Used by a program to indicate it is using a particular device or file
| |—-log - Log files from programs such as login and syslog which logs all logins,
| | logouts, and other system messages.
| |—-run - Files that contain information about the system that is valid until the system is
| | next booted
| |—-spool - Directories for mail, printer spools, news and other spooled work.
| |—-tmp - Temporary files that are large or need to exist for longer than they should in
| | /tmp.
| |—-catman - A cache for man pages that are formatted on demand
|—mnt - Mount points for temporary mounts by the system administrator.
|—tmp - Temporary files. Programs running after bootup should use /var/tmp.

The Package Manager

Synaptic, the Ubuntu package manager, is one of the most powerful features of the operating system. On Windows, you are probably used to searching endlessly for the right site to download the program you need. You then manually install it. A few months later, you have no idea if an update has been released.

Synaptic changes all of that. The package manager maintains a fairly comprehensive list of programs available to you. You can search for anything that you might want and install it right there. Synaptic maintains a database of what applications that you have installed and automatically informs you when an update is ready. It’s simple to use, just open it from the System->Administration menu.

Click search or use the categories on the left to find what you are looking for. If you want to install it, click the checkbox. When you have chosen all of the programs that you want, click “Apply.” You’re done. See, simple!

Programs Available

You’ll probably be pleasently surprised to find that some of the programs that you’ve used before are available in Linux. For others, there are powerful open-source alternatives.

The Internet

For web browsing, the default option open to you is Mozilla’s Firefox browser. You are probably used to it already, as millions and millions of Windows users have already switched to it. Its open-source nature has made it far more extendable and far less of a security risk than Microsoft’s Internet Explorer.

If you are an AIM user, take a look at Pidgin messenger. It is an open-source version of AIM, with all of the features of the standard version.

Word Processing/Office

Ubuntu includes OpenOffice.org as its office suite. Just like Microsoft Office, OpenOffice has applications for word processing, spreadsheets, presentations, and databases. OpenOffice is compatable with files that have been created in Microsoft Office, so all of your older work can still be seen and edited.

Music

There are dozens of music applications in Linux, but we have to recommend Amarok without a doubt. Amarok’s interface should be familiar to any iTunes user. Your library is right there, you cna easily create your own playlists. There is built-in last.fm integration. Own an iPod? Amarok’s iPod support it top-notch.

Image Editing

The GIMP image editor is the closest thing to Photoshop in Ubuntu. It obviously isn’t as feature-rich, but it is completely free. You can also write your own image-altering filters.