2.0 Getting Started

Since most people have never even seen Linux, it might take a while to get used to. If you have used MS-DOS you should be able to recognize some similarities. Those who have experience using other types of UNIX's should adapt right away as Linux is almost the same in every way.

For those people who have only used windows be prepared to relearn most ways of doing things. You may not be used to using a command line, which is used for most of the basic programs such as listing the files in a directory, and moving and copying files. If you don't like the text based environment you will have to get used to it, although there are many graphical utilities that can do just about anything you want.

2.1.0 Logging into the machine

Linux is a multi-user operating system. This means that many people can log into the system and use it simultaneously. Each user is given certain permissions on what files and programs they can or can't run, they may also have different shells, environment variables, etc.

When you connect to, or boot-up, your system you will be prompted to enter a user name and password:

Redhat 7.2
Kernel 2.4.18 on i386

host login: root

password:

[root@host ~]#

2.2.0 Users

In the above login example we logged into the system as the user root. The root user is the super-user of the system. Root generally is used to do administrative tasks on the system, install, uninstall, and configure programs for the users. The root user can modify any of the files on the system, which is why you should know what you are doing when using the root account. If you have your own computer with Linux installed on it, you will have access to the root account. The password should have been set during the installation of your distribution. The root account should rarely be used as it can cause serious damage to the system if you are not careful.

You may be asking then, "How do I add a standard user to work with?". This can be done by using the adduser program, while you are logged into the system as root. Simply type adduser into the command-line. He is an example, we will add the user bob to the system.

[root@host /home]# adduser bob

2.3.0 Setting up the environment

Lets take a second to look at how to use environment variables to specify paths, aliases, and other useful information that we might need.

Variables are used by the shell to temporarily hold information, this way the user can save time by not having to specify something every time a program needs to be found or what the command line should look like. To see a list of all the variables that are set type set in your command prompt, this should list all the variables and their values in the form of "variable=value". If you ever want to check the value of just one variable you can type echo $variablename, where $variablename is the name of variable with the $ in front of it. Typing echo $SHELL will output /bin/tcsh (or whatever your shell program is), the value for the variable SHELL.

We can create and modify variables to give us more flexibility when working with the shell. To create a usable variable we have to declare the name of the variable and then assign a value to it. I will be showing how to do this under the tcsh shell, other shells follow a similar way of declaring variables and usually you can find out how by typing man yourshell.

To change the value of a variable you would type the name of the varible and then assign it a value using the = sign. Here is an example where we tell the shell a path.

[bob@host ~]$ set path=(/bin /usr/local/bin /opt/gnome/bin)
[bob@host ~]$ echo $path
/bin /usr/local/bin /opt/gnome/bin
[bob@host ~]$

set path=($path /bin /usr/local/bin /opt/gnome/bin)

set $prompt="[${USER}@${HOST} %.] "

${USER}
This simply takes whatever that value of the environment variable $USER is. If you type echo $USER it should return your current username.

${HOST}
This pretty much is the same as ${USER} except that it returns your host name.

%.
This prints the current directory that you are in.

2.3.2 Configuration files

Lets begin with an example on configuration files and what they are. These are the files in the user's home directory that begin with a '.'. Most of the time when the user logs into their account a file is read be the shell program to set up user settings such as paths, what the command prompt looks like, and other settings that change from user to user.

For an example we will take a look at the configuration file for the tcsh shell. This file is called .tcshrc under the users home directory. If you are using another shell other than tcsh the file will be different but usually will follow the same naming scheme, i.e. Bash uses .bashrc or .bash_profile as a configuration file. So, once inside your home directory use the command ls -al to display all the contents of the current directory.

[bob@host ~]$ ls -al
total 8
drwxr-xr-x 2 bob other 512 Apr 22 16:03 .
drwxr-xr-x 9 root root 512 Apr 22 15:54 ..
-rw------- 1 bob other 397 Apr 22 16:09 .ssh
-rw-r--r-- 1 bob other 20 Apr 22 16:09 .tcshrc
[bob@host ~]$


[bob@zedd ~] cat .tcshrc
#!/bin/tcsh
set path=(/usr/local/bin /usr/bin /opt/gnome/bin)
set prompt="[${USER}@${HOST} %.] "
alias ls 'ls -la'
[bob@zedd ~]