Chapter 2: Linux File System & Essential Commands

1. Introduction

Every Linux administrator spends a significant amount of time navigating the filesystem[cite: 38]. Configuration files, application data, log files, software packages and user documents are all stored within a single, well-defined directory hierarchy[cite: 38]. Understanding this structure is one of the most valuable skills for beginners because nearly every command you learn later depends on knowing where files are located[cite: 38].

2. Understanding the Linux Filesystem

Unlike Windows, Linux does not organize storage using drive letters such as C: or D:[cite: 38]. Instead, everything begins from a single top-level directory called the root directory (/)[cite: 38]. Additional disks, USB devices and network filesystems are attached somewhere under this hierarchy through a process called mounting[cite: 38].

                /
      ├── boot
      ├── dev
      ├── etc
      ├── home
      ├── opt
      ├── proc
      ├── root
      ├── tmp
      ├── usr
      └── var
                  

3. Important Linux Directories

4. Absolute vs Relative Paths

An absolute path always starts from /, while a relative path starts from your current working directory[cite: 38].

Absolute: /home/student/Documents/report.txt
Relative: Documents/report.txt

5. The pwd Command

The pwd command prints the current working directory[cite: 38].

$ pwd
/home/student

6. The cd Command

The cd command changes your current directory[cite: 38].

7. Hands-on Practice

1. Navigate to /var[cite: 38].
2. Return to your home directory[cite: 38].
3. Move to the root directory[cite: 38].
4. Use cd - to return[cite: 38].
5. Verify every step using pwd[cite: 38].

9. Creating Directories with mkdir

mkdir project
mkdir logs backup temp
mkdir -p /tmp/demo/test

The -p option creates parent directories automatically if they do not already exist[cite: 38].

10. Creating Files with touch

touch notes.txt
touch file1 file2 file3
touch /tmp/app.log

Besides creating empty files, touch also updates file timestamps[cite: 38].

11. Copying Files with cp

cp file1 file2
cp report.txt /backup/
cp -r project backup_project

12. Moving and Renaming Files with mv

mv old.txt new.txt
mv report.txt /archive/
mv *.log /var/log/archive/

The same command is used both for renaming files and moving them to a different directory[cite: 38].

13. Removing Files with rm

rm file.txt
rm -i file.txt
rm -r directory
rm -rf temp_directory

15. Searching via find and locate

The find command searches directories based on name, type, size, and modifications[cite: 38].

find /etc -name sshd_config
find . -name "*.log"

16. Hard Links vs Symbolic Links

17. Inspecting Files with stat and file

The stat command displays detailed metadata including permissions, inode, timestamps and ownership[cite: 38]. The file command determines the actual file type instead of relying on the filename extension[cite: 38].

18. Disk Usage Commands (df, du)

Use df -h to check free and used space on mounted filesystems[cite: 38]. Use du -sh to determine which directories consume the most storage footprint[cite: 38].