A free Basic UNIX-training with muLinux

The First Unix Commands

Login Prompt

After the computer has loaded mulinux, the login prompt appears.

mulinux login: _

We log in as root (superuser) and have full command authority over the computer.

mulinux login: root

The prompt awaits input.

/# _

Every time the prompt appears, we can enter UNIX commands. Those comfortable with DOS, will be at home here. Indeed, Microsoft began with an old version of the operating system CP/M86 bought from Digital Research which contained some Unix functions.

Instruction input

Unlike DOS, Unix commands are substantially more efficient and, in addition, more complex. However the syntax of these commands has hardly changed in the last 20 years. This stability is found in no other operating system! I think these UNIX commands will still be with us 20 years from now. These commands work with all computers using the Unix operating system (Linux, BSD, Solaris, NeXT, SCO, BeOS...). If you learn a new UNIX command every time you restart Windows, you will soon qualify as a Unix System Administrator.

Graphic user interfaces are convenient, however complex operating systems cannot be implemented perfectly. If the graphic interface does not function, one must be able to fall back on UNIX commands. With Unix, one can log in over a network, on another computer, and input UNIX commands (remote maintenance). A graphic interface is not available in this situation. Thus, the knowledge gained from learning these commands has many advantages.

That said, let us input our first command. With our first date with UNIX we type date on:

/# date

Press the Enter - key after typing each command.

The instruction date displays the current date and time-of-day. Unix differentiates between upper and lower case. Windows 9x/NT does not. An error in case returns command not found.

Here is another instruction:

/ # dmesg

This command outputs the kernel messages. These messages may be confusing at first. Don't be concerned at the moment with their contents. It is enough that you know how to access this information.

Most UNIX commands or programs accept arguments, [ ctrl ] [ C ] will abort a command and return to the system prompt, the argument [ ctrl ] [ L] will clear the display when necessary.

Screen Scrolling

To scroll the screen display we press the keys [ SHIFT ] and [ page up] .

[ SHIFT ] is the shift key for upper and lower case.
[ page up] is located above the cursor [ arrow] keys

[ SHIFT ] and [ page down ] scrolls in the opposite direction.

Repeating Instructions, Command Line History

Typing long command line instructions can be complex. Retyping them can introduce errors and takes time. Therefore this has been simplified with the command line history buffer which saves the commands you enter. If we want to repeat a command, we do not have to retype it. If we want to display the time again:

Pressing the [ Cursor up] (the up-arrow key), the command date appears again. Press Enter and the instruction is executed once more. The[ Cursor down key ] takes us downward in the instruction history list.

The keys [ cursor left] and [ cursor right] are for editing instructions and correcting typing errors. Characters can simply be inserted, or deleted using the [ Backspace ] key.

Instruction with instruction mode

Some instructions possess an instruction mode. Where the instruction called waits for and accepts user input. Until we exit the instruction, no UNIX commands can be input. An example is bc.

bc calls a calculator program. The cursor changes and waits for data to be entered for example: 4+5 or 9*10 .

/ # bc
> 4+5
9

> 9*10
90
>

The calculator mode terminates with the simultaneous pressing of the keys [ ctrl] and [ d ] returning to the system prompt.

> [Ctrl] [ d ]
/# _

Switching between consoles (terminals)

What if we want to execute an instruction while another instruction is still active? Linux allows us to switch between several consoles (terminals). The basis for this is the multi-user ability of Unix. We press the following key combination:

[ Tab] [ F2 ]

[ Tab] the key is at the upper left, [ F2] the second key is in the top row of function keys.
With these two keys, one changes to the second console. There, we log in as root also, in order to be able to input UNIX commands. We try again the calculator command:

/# bc
> 12/3
4

We can return to the first console with the following combination.

[ Tab ] [ F1 ]

Here we are able to execute the date command again, while the calculator still runs on console 2.

/ # date

muLinux offers normally 6 consoles, which are addressed via the following combinations of keys:

[ Tab ] [ F1 ]... [ Tab ] [ F6 ]

Log out (logout)

To terminate work on a console type exit.

/# exit and press enter.

Alternatively, the key combination[ ctrl] [ d] may be used.