LINUX | Info & Instructions

Why Linux?

Free and open source:
Linux distributions are usually available for free, and the source code is freely available.

Safe and stable:
Linux is known for its security and reliability.

Flexibility:
From minimalist setups to complex server architectures, Linux adapts to your needs.

Large Community:
There is a huge community that will help you with words and deeds.

Linux is much more than just an operating system – it’s a community, a philosophy, and a limitless playground for tech enthusiasts. With the increasing popularity of open source technologies, Linux is becoming increasingly important, both in the private and professional spheres. On this page, we would like to help you find your way around the world of Linux – whether you are a beginner or an experienced user.

LINUX | SHELL at a glance

– the most important commands summarized

The shell is the central control element in Linux systems and allows users to enter and execute commands in plain text. This type of interaction is extremely efficient, flexible and in many cases the only way to make in-depth system interventions for many tasks. While modern desktop environments provide graphical user interfaces, the shell is often the means of choice in system administration and software development.

What is a shell anyway?

A shell is basically a program that receives commands, interprets them, and outputs the result. In Linux, the most popular and widely used shell is Bash (Bourne Again Shell). However, there are also other shell variants such as Zsh, Fish or Dash, some of which offer advanced or specialized functions.

Shell Commands

Path Structures and Navigation

Unlike Windows, Linux does not know drive letters. The top level of the file system is the root directory (). To find your way around, the following directories are important:

• / – Root directory, root of the file system
• /home – Default directory for users
• /etc – system configuration files
• /var – Variable data (logs, temporary files)
• /bin, /usr/bin – System Utilities and Applications
• /lib, /usr/lib – System Libraries

For example, to switch to the directory /etc , use cd /etc. For a quick switch back to the home directory, a cd ~.

Pipes and Redirects

One of the most powerful concepts of the Linux shell is the piping of commands and the targeted redirection of inputs and outputs.

• Pipes(|) pass the output of the first instruction to the input stream of the next command:
  ls -l | grep '.txt' Here lists ls -l all entries and grep filters only by rows with .txt.
• Redirects are used to redirect outputs to files or use files as inputs:
  • > overwrites a file with the output:
    ls -l > output.txt
  • >> appends to an existing file:
    echo "Neuer Eintrag" >> datei.txt
  • < uses a file as input:
    wc -l < datei.txt

Shell Scripts

Shell scripts are simple text files that contain commands in the order in which they are executed. They enable the automation of recurring tasks. Example of a simple script:

#!/bin/bash
echo "Hallo, Welt!"

1. Create a file, e.g. test.sh
2. Make script executable: chmod +x test.sh
3. Run with ./test.sh

Useful tips to get you started

1. Tab completion
   Use the Tab key to autocomplete file names or commands.
   
2. Troubleshooting with history
   You can view your past commands via history . This makes it possible to uncover sources of error more quickly or to quickly re-execute frequently used commands.
   
3. Structure of an alias
   Aliases can be used to shorten complicated or long commands. For example, a often can be used by depositing in ls -la the ~/.bashrc :
   a lias ll='ls -la'
   
4. Explore More Shells
   Each shell has its own special features. While Bash is the standard, Zsh, for example, offers many convenience features such as auto-completion, syntax highlighting , and correction suggestions.

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