https://github.com/heynzar/bash-and-linux-journey
⚡ This is a friendly guide for anyone who wants to explore and learn Linux, master command-line tools, and dive into the world of bash scripting.
https://github.com/heynzar/bash-and-linux-journey
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⚡ This is a friendly guide for anyone who wants to explore and learn Linux, master command-line tools, and dive into the world of bash scripting.
- Host: GitHub
- URL: https://github.com/heynzar/bash-and-linux-journey
- Owner: heynzar
- Created: 2025-01-02T21:03:19.000Z (over 1 year ago)
- Default Branch: main
- Last Pushed: 2025-01-22T19:53:34.000Z (over 1 year ago)
- Last Synced: 2025-03-03T14:13:12.019Z (over 1 year ago)
- Topics: bash, bash-script, command-line, linux, os
- Language: Shell
- Homepage:
- Size: 173 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# 🐧 Bash and Linux Journey
This project started as my journey to learn Linux and Bash scripting as part of a university module.
Along the way, I realized how valuable this knowledge could be, so I decided to enhance it and share it with everyone.
This guide serves as a solid starting point for anyone looking to understand Linux fundamentals and dive into Bash scripting.
---
## 📚 Table of Contents
1. [Linux Fundamentals](#1-linux-fundamentals)
1.1. [Basic Commands](#11-basic-commands)
1.2. [File Permissions](#12-file-permissions)
1.3. [Users and Groups](#13-users-and-groups-management)
1.4. [Process Management](#14-process-management)
1.5. [Regular Expressions](#15-regular-expressions)
2. [Bash Fundamentals](#2-bash-fundamentals)
2.1. [Introduction to Bash Scripts](#21-introduction-to-bash-scripts)
2.2. [Variables](#22-variables)
2.3. [Special Variables](#23-special-variables)
2.4. [Control Flow](#24-control-flow)
2.5. [Numbers and Strings](#25-numbers-and-strings)
2.6. [Loops and Iteration](#26-loops-and-iteration)
2.7. [Functions](#27-functions)
3. [Linux Fundamentals Test](#3-linux-fundamentals-test)
3.1. [Easy](#31-easy-linux-questions)
3.2. [Medium](#32-medium-linux-questions)
3.3. [Hard](#33-hard-linux-questions)
4. [Practical Scripts](#4-practical-scripts)\
4.1. [Directory Organizer](#4-practical-scripts)\
4.2. [System information](#4-practical-scripts)
4.3. [Todo List](#4-practical-scripts)
5. [Acknowledgments]("#5-acknowledgments")
6. [Contact]("#6-contact")
---
## 1. **Linux Fundamentals**
Learn the core concepts of Linux, from basic commands to managing processes. Files included:
- [`01_basic_commands.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/01_Linux_Fundamentals/01_basic_commands.md): Overview of essential Linux commands.
- [`02_file_permissions.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/01_Linux_Fundamentals/02_file_permissions.md): Managing file and directory permissions.
- [`03_users_and_groups.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/01_Linux_Fundamentals/03_users_and_groups.md): User and group management.
- [`04_process_management.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/01_Linux_Fundamentals/04_process_management.md): Handling system processes.
- [`Regular_Expressions.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/01_Linux_Fundamentals/Regular_Expressions.md): Introduction to regular expressions in Linux.
## 1.1 **Basic Commands**
This is a quick summary of basic Linux commands. For detailed explanations and examples, check the full guide [`01_basic_commands.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/01_Linux_Fundamentals/01_basic_commands.md).
| ID | Command | Description |
| --- | -------- | ------------------------------------------------------ |
| 1 | `pwd` | Print current working directory path |
| 2 | `cd` | Change between directories |
| 3 | `ls` | List directory contents and their properties |
| 4 | `mkdir` | Create new directories |
| 5 | `cat` | Display, combine, and create text files |
| 6 | `less` | View text files with forward and backward navigation |
| 7 | `more` | View text files with forward-only pagination |
| 8 | `head` | Display the beginning of files |
| 9 | `tail` | Display the end of files |
| 10 | `touch` | Create empty files or update file timestamps |
| 11 | `cp` | Copy files and directories |
| 12 | `mv` | Move or rename files and directories |
| 13 | `rm` | Remove files and directories |
| 14 | `tr` | Translate or delete characters in text |
| 15 | `wc` | Count lines, words, and characters in files |
| 16 | `ln` | Create hard or symbolic links between files |
| 17 | `locate` | Find files by name using system database |
| 18 | `find` | Search for files and directories with complex criteria |
| 19 | `grep` | Search for text patterns in files |
| 20 | `cut` | Extract sections from lines of files |
| 21 | `awk` | Pattern scanning and text processing language |
| 22 | `sort` | Sort lines of text files |
| 23 | `uniq` | Report or omit repeated lines |
| 24 | `diff` | Compare files line by line |
| 25 | `cmp` | Compare files byte by byte |
## 1.2 **File Permissions**
This is a quick summary of file permissions in Linux. For detailed explanations and examples, check the full guide [`02_file_permissions.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/01_Linux_Fundamentals/02_file_permissions.md).
| ID | Command | Description |
| --- | --------- | ------------------------------------------- |
| 1 | `chmod` | Change permissions of files and directories |
| 2 | `chown` | Change the owner of files and directories |
| 3 | `chgrp` | Change the group of files and directories |
| 4 | `umask` | Control default permission settings |
| 5 | `getfacl` | Display Access Control Lists (ACLs) |
| 6 | `setfacl` | Modify Access Control Lists (ACLs) |
## 1.3 **Users and Groups Management**
This is a quick summary of users and groups management in Linux. For detailed explanations and examples, check the full guide [`03_users_and_groups.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/01_Linux_Fundamentals/03_users_and_groups.md).
| ID | Command | Description |
| --- | ---------- | --------------------------------------- |
| 1 | `useradd` | Create new users in the system |
| 2 | `usermod` | Modify existing user accounts |
| 3 | `userdel` | Delete users from the system |
| 4 | `passwd` | Manage user passwords |
| 5 | `groupadd` | Create new groups |
| 6 | `groupmod` | Modify existing groups |
| 7 | `groupdel` | Delete groups from the system |
| 8 | `gpasswd` | Manage group members and administrators |
| 9 | `id` | Show user and group IDs |
| 10 | `groups` | Display group membership |
| 11 | `who` | Show logged-in users |
| 12 | `w` | Detailed view of logged-in users |
## 1.4 **Process Management**
This is a quick summary of process management in Linux. For detailed explanations and examples, check the full guide [`04_process_management.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/01_Linux_Fundamentals/04_process_management.md).
| ID | Command | Description |
| --- | ------------- | ------------------------------------------- |
| 1 | `ps` | Display information about running processes |
| 2 | `top` | Real-time view of system processes |
| 3 | `kill` | Send signals to processes |
| 4 | `nice/renice` | Manage process priority |
| 5 | `jobs/bg/fg` | Manage background and foreground jobs |
| 6 | `crontab` | Schedule and manage automated tasks |
| 7 | `htop` | Enhanced interactive process viewer |
| 8 | `free` | Display memory usage |
| 9 | `uptime` | Show system load and uptime |
## 1.5 **Regular Expressions**
This is a quick summary of regular expressions in Bash. For detailed explanations and examples, check the full guide [`Regular_Expressions.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/01_Linux_Fundamentals/Regular_Expressions.md).
| ID | Pattern | Description |
| --- | ------- | ---------------------------------------------------------- |
| 1 | `.` | Matches any single character |
| 2 | `[]` | Matches any character within the brackets |
| 3 | `[^]` | Matches any character not within the brackets |
| 4 | `-` | Defines a range of characters within brackets |
| 5 | `*` | Matches zero or more occurrences of the previous character |
| 6 | `+` | Matches one or more occurrences of the previous character |
| 7 | `?` | Matches zero or one occurrence of the previous character |
| 8 | `^` | Matches the start of a line |
| 9 | `$` | Matches the end of a line |
| 10 | `{}` | Specifies exact number of occurrences |
| 11 | `\` | Escapes special characters |
| 12 | `()` | Groups patterns together |
| 13 | `\|` | Alternation (OR operator) |
| 14 | `\b` | Word boundary |
| 15 | `\d` | Matches any digit (equivalent to [0-9]) |
| 16 | `\w` | Matches any word character (equivalent to [a-zA-Z0-9_]) |
| 17 | `\s` | Matches any whitespace character |
---
## 2. **Bash Fundamentals**
A step-by-step guide to Bash scripting, covering everything from the basics to advanced concepts. Files included:
- [`01_Introduction_Bash_Scripts.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/01_Introduction_Bash_Scripts.md): Getting started with Bash scripts.
- [`02_Variables.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/02_Variables.md): Understanding variables in Bash.
- [`03_Special_variables.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/03_Special_variables.md): Overview of special variables.
- [`04_Control_Flow.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/04_Control_Flow.md): Conditional statements and control flow.
- [`05_Numbers_and_Strings.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/05_Numbers_and_Strings.md): Working with numbers and strings.
- [`06_Loops_and_Iteration.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/06_Loops_and_Iteration.md): Looping constructs in Bash.
- [`07_Functions.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/07_Functions.md): Creating and using functions in Bash.
## 2.1 Introduction To Bash Scripts
**Core Concepts**
A Bash script is a text file containing a sequence of shell commands for automated execution. Think of it as a recipe for your computer to follow.
**Essential Components**
1. **Shebang Line**
- Every script starts with `#!/bin/bash`
- Must be the first line of the file
2. **Basic Script Creation Process**
```bash
nano script_name.sh # Create/edit script
chmod +x script_name.sh # Make executable
./script_name.sh # Run script
```
**Best Practices**
- Include clear comments explaining the script's purpose
- Use descriptive filenames (e.g., `backup_photos.sh` instead of `script1.sh`)
- Avoid spaces around equal signs in assignments (`name="John"`, not `name = "John"`)
**Script Structure Example**
```bash
#!/bin/bash
# Script purpose
# Author
# Date
# Main commands
command1
command2
# End of script notification
```
For detailed examples and practices, explore the full guide [`01_Introduction_Bash_Scripts.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/01_Introduction_Bash_Scripts.md).
## 2.2 Variables
Variables are placeholders for storing data in Bash scripts.
**Key takeaways:**
- Assign values with `=` (no spaces).
- Use meaningful names (e.g., `user_name` not `a`).
- Access values with `$`, like `$name`.
**Types include:**
- **Shell Variables:** Script-local variables.
- **Environment Variables:** System-wide variables like `$HOME` and `$USER`.
To capture user input, use `read`, optionally with prompts or timeouts. Combine these with command substitution to store output from commands like `date`.
For detailed examples and practices, explore the full guide [`02_Variables.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/02_Variables.md).
## 2.3 Special Variables
**Special Variables Overview**
Key shell variables and their purposes:
- `$0` - Script name
- `$1` to `$9` - Script arguments (positional parameters)
- `$#` - Number of arguments
- `$*` and `$@` - All arguments
- `$?` - Last command's exit status
- `$$` - Current process ID
- `$!` - Last background process ID
**Parameter Handling**
```bash
#!/bin/bash
name=${1:-"Default"} # Default value if parameter is unset
length=${#1} # Parameter length
substring=${1:0:3} # Extract substring
```
**Best Practices**
- Quote variables when using them: `"$variable"`
- Check required arguments:
```bash
if [ $# -lt 2 ]; then
echo "Usage: $0 arg1 arg2"
exit 1
fi
```
- Use meaningful variable names
- Provide default values for optional parameters
For detailed examples and practices, explore the full guide [`03_Special_variables.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/03_Special_variables.md).
## 2.4 Control Flow
### 1. If Statements
```bash
if [ condition ]; then
# code
elif [ condition ]; then
# code
else
# code
fi
```
### 2. Case Statements
```bash
case $variable in
pattern1) commands ;;
pattern2) commands ;;
*) default commands ;;
esac
```
### Condition Types
1. **Numeric Comparisons**
- `-eq` - Equal to
- `-ne` - Not equal
- `-gt` - Greater than
- `-lt` - Less than
- `-ge` - Greater than or equal
- `-le` - Less than or equal
2. **String Tests**
- `=` - Equal to
- `!=` - Not equal to
- `-z` - Empty string
- `-n` - Non-empty string
3. **File Tests**
- `-e` - Exists
- `-f` - Regular file
- `-d` - Directory
- `-r` - Readable
- `-w` - Writable
- `-x` - Executable
For detailed examples and practices, explore the full guide [`04_Control_Flow.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/04_Control_Flow.md).
## 2.5 Numbers and Strings
### Arithmetic Operations
1. **Using let**
```bash
let sum=5+3
let product=4*3
```
1. **Using expr**
```bash
result=$(expr 10 + 5)
product=$(expr 5 \* 3)
```
1. **Double Parentheses**
```bash
sum=$((5 + 3))
power=$((2 ** 3)) # Exponentiation
```
### String Operations
**Basic String Manipulation**
- Length: `${#string}`
- Concatenation: `full_name="$first $last"`
- Substring: `${string:start:length}`
- Uppercase: `${string^^}`
- Lowercase: `${string,,}`
For detailed examples and practices, explore the full guide [`05_Numbers_and_Strings.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/05_Numbers_and_Strings.md).
## 2.6 Loops and Iteration
### Loop Types
**1. For Loops**
```bash
# Basic syntax
for i in 1 2 3 4 5; do
echo "$i"
done
# Range syntax
for i in {1..5}; do
echo "$i"
done
# C-style syntax
for ((i=1; i<=5; i++)); do
echo "$i"
done
```
**2. While Loops**
```bash
# Basic while
counter=1
while [ $counter -le 5 ]; do
((counter++))
done
# Reading files
while read -r line; do
echo "$line"
done < file.txt
```
### Control Statements
- `break` - Exit the loop
- `continue` - Skip to next iteration
For detailed examples and practices, explore the full guide [`06_Loops_and_Iteration.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/06_Loops_and_Iteration.md).
## 2.7 Functions
### 1. Basic Function Structure
- Define a function using:
```bash
function_name() {
# Function code
}
```
- Call the function by its name.
### 2. Functions with Parameters
- Access parameters using `$1`, `$2`, etc.
- Use `$@` to loop through all parameters.
### 3. Return Values
- Use `return` for exit codes (success: `0`, failure: non-zero).
- Use `echo` to output values for further processing.
### 4. Local Variables
- Use `local` keyword to restrict variable scope within functions.
For detailed examples and practices, explore the full guide [`07_Functions.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/02_Bash_Fundamentals/07_Functions.md).
---
## 3. **Linux Fundamentals Test**
Test your understanding of Linux basics with three levels of challenges:
- [`01_Easy.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/03_Linux_Fundamentals_Test/01_Easy.md): Simple tasks to build confidence.
- [`02_Medium.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/03_Linux_Fundamentals_Test/02_Medium.md): Intermediate challenges to test your skills.
- [`03_Hard.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/03_Linux_Fundamentals_Test/03_Hard.md): Advanced problems, if you conquer these, you're ready for anything!
## 3.1 Easy Linux Questions
**01 Basic Commands**
1. What is the command to display the current working directory?
2. How do you list all files and directories, including hidden ones?
3. Which command is used to create a new directory?
4. How do you display the content of a text file?
5. What command is used to move or rename a file?
**02 File Permissions**
6. How do you check the permissions of a file or directory?
7. What does the permission `rwxr-xr--` mean?
8. Which command is used to change the ownership of a file?
9. How do you change file permissions using symbolic notation (e.g., add write permission to the owner)?
10. What is the numeric value of `rw-r--r--` in octal notation?
**03 Users and Groups**
11. Which command is used to display information about the currently logged-in user?
12. How do you switch to a different user account?
13. What command is used to add a new user to the system?
14. How can you check the groups a user belongs to?
15. Which file contains the list of all users on a system?
**04 Process Management**
16. What command is used to display a list of running processes?
17. How do you terminate a process using its PID?
18. Which command shows the real-time CPU and memory usage of processes?
19. How do you run a command in the background?
20. What is the command to bring a background process to the foreground?
I've organized the answers in this file [`01_Easy.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/03_Linux_Fundamentals_Test/01_Easy.md).
## 3.2 Medium Linux Questions
**01 Basic Commands**
1. How do you navigate to the root directory from the current working directory?
2. What is the difference between `ls` and `ls -l`?
3. How do you create a new file without using a text editor?
4. Which command is used to view the first 10 lines of a file, and how do you change the number of lines displayed?
5. What is the difference between `more` and `less` commands?
6. How do you display all files in a directory, including hidden ones, sorted by modification time?
7. How do you copy multiple files to a directory?
8. Which command allows you to replace all occurrences of a character in a file with another character?
9. How can you count the number of lines, words, and characters in a file?
10. How do you find the location of a command’s executable file?
11. Which command helps you find files by name in the current directory and its subdirectories?
12. What is the difference between `grep` and `find` commands?
13. How do you display only unique lines from a file?
14. What command can you use to compare two files and highlight the differences?
15. How do you sort the lines of a file in reverse order?
16. Which command allows you to display specific columns from a file?
17. How can you combine the output of two files line by line?
18. What is the purpose of the `ln` command, and how do you create a symbolic link?
19. How do you permanently delete a directory and all its contents?
20. How can you search for a specific pattern in all `.txt` files within a directory?
**02 File Permissions**
21. How do you recursively change permissions for all files in a directory?
22. What does the sticky bit do, and how do you set it on a directory?
23. How can you set default permissions for newly created files using `umask`?
24. What command is used to change both the owner and group of a file at once?
25. How do you remove execute permission for the group and others from a directory?
**03 Users and Groups**
26. What is the difference between `useradd` and `adduser` commands?
27. How do you delete a user along with their home directory?
28. Which command is used to lock a user account?
29. How can you change the primary group of a user?
30. What is the purpose of the `/etc/group` file?
**04 Process Management**
31. How do you display the parent process ID (PPID) of a process?
32. Which command is used to schedule a job to run at a specific time?
33. What is the difference between `kill` and `killall` commands?
34. How do you identify and kill processes consuming the most CPU resources?
35. How can you view the environmental variables of a specific process?
I've organized the answers in this file [`02_Medium.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/03_Linux_Fundamentals_Test/02_Medium.md).
## 3.3 Hard Linux Questions
**01 Basic Commands**
1. How do you navigate to a directory with spaces in its name?
2. What command would you use to count the number of files and directories within a specific directory?
3. How can you view the last 15 lines of a file and keep monitoring it for new lines?
4. Which command allows you to replace a specific string in a file with another string and save the changes?
5. How can you list all files in a directory and its subdirectories, along with their sizes?
6. What is the difference between a hard link and a symbolic link, and how do you create each?
7. How do you find and delete all `.log` files within a directory and its subdirectories?
8. How can you sort the contents of a file numerically and remove duplicate lines?
9. What command can you use to display the 5 most frequently occurring words in a file?
10. How do you find the total size of all `.txt` files within the current directory?
**02 File Permissions**
11. How do you set permissions so that only the owner can read, write, and execute a file, while the group and others have no permissions?
12. What command is used to find all files owned by a specific user?
13. How do you ensure that new files created in a directory inherit the group ownership of the directory?
14. How can you change the permissions of a file to match those of another file?
15. Which command allows you to find files with the SUID bit set?
**03 Users and Groups**
16. How do you list all users currently logged into the system?
17. What command would you use to check the last login time of a user?
18. How can you add a user to multiple groups at once?
19. How do you change the password expiration policy for a specific user?
20. What is the purpose of the `/etc/shadow` file, and who has access to it?
**04 Process Management**
21. How can you run a command that continues to execute even after you log out?
22. How do you monitor the number of processes run by a specific user?
23. Which command allows you to send a specific signal (e.g., `SIGTERM`) to a process by name?
24. How do you schedule a recurring job to run every day at 2 AM?
25. What is the difference between `nice` and `renice` commands?
I've organized the answers in this file [`03_Hard.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/03_Linux_Fundamentals_Test/03_Hard.md).
---
## 4. **Practical Scripts**
Some real-world examples of Bash scripts to reinforce learning and showcase practical use cases. Check those files, or run the scripts on your machine to see how they work.
- [`directory_organizer.sh`](https://github.com/heynzar/bash-and-linux-journey/blob/main/04_Practical_Scripts/directory_organizer.sh): Automatically organize files into directories based on their type.
- [`system_info.sh.md`](https://github.com/heynzar/bash-and-linux-journey/blob/main/04_Practical_Scripts/system_info.sh): Display detailed system statistics at a glance.
- [`todo.sh`](https://github.com/heynzar/bash-and-linux-journey/blob/main/04_Practical_Scripts/todo.sh): A simple script to manage your tasks from the terminal.
## 5. Acknowledgments
Special thanks to these YouTube channels for their exceptional knowledge and tutorials on Linux and Bash:
- [Learn Linux TV](https://www.youtube.com/@LearnLinuxTV)
- [Network Chuck](https://www.youtube.com/@NetworkChuck)
Their content has been invaluable in the creation of this guide.
## 6. Contact
Nzar - [@heynzar](https://x.com/heynzar) - heynzar@gmail.com
Project Link: [https://github.com/heynzar/bash-and-linux-journey](https://github.com/heynzar/bash-and-linux-journey)