Slide 1: The Linux Operating System

Lecture 2

Uli Raich

Slide 2: Starting the Linux System

This is how the screen may loop like after some programs have been started

Slide 3: Linux Distributions

Linux comes in many flavors (distributions) which may be different of how they are configured,
their desktop, their software repository, their target user community

beginners, gurus, programmers, desktop, server …

Here are some distributions:
Ubuntu (which we use), Mint, Debian, RedHat, Fedora, Kali...

Slide 4: Linux versus Windows

Linux can be downloaded and installed for free

The sources of the OS can be accessed freely

Linux has a window system based on X11 and has most facilities Windows offers

For certain commercial hardware there are no Linux drivers (caution!)

Writing your own Linux driver is possible but often the manufacturers do not open the
hardware specs (register meaning, initialization procedure…)
which makes this a very tedious job.

Programmers mostly use the command line interface something that is hardly ever used in Windows.
The file system layout on disk is different (ext4 vs ntfs) but there exist drivers on both systems

reading and writing the others files systems

Slide 5: Linux Command Line

When you start up a terminal window, you start a command shell with it.
We will be using bash

When you type a command, bash will check if it is a command implemented in bash,
in which case it is executed immediately,
otherwise a new process is created, the command loaded and executed

After termination of the command the process is removed again.

Either bash waits for termination of the process
or it is run in parallel (“&” after the command)

Where are the commands and how many are there?

Slide 6: Most used Linux Commands

Here are a few very frequently used comnmands

Command	Action
ls	List directory content
cat, less, more	Print content of a text file
mkdir	Create a directory
cd	Change working directory
pwd	Print current working directory
echo	Print variable
vi, nano, emacs, gedit ...	Edit a text file
rm, rmdir	Remove a file / directory
grep	Search for a string in files

Have a look in /bin /usr/bin.

The environment variable PATH tells the system where to look for commands.
The number of commands is unlimited since you can write your own commands
and include them into the system.

-- Uli Raich - 2017-09-05

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