EP6: Linux Filesystem Structure

In this episode, we explore the basic structure of the Linux filesystem, what each top-level folder means, and why it's important — especially for the RHCSA exam.

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📁 What is the Linux Filesystem?

Linux organizes everything — files, folders, devices — into a single root tree that starts from / (root directory).

It’s like your C:\ drive in Windows, but without letters (D:, E:, etc).

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🗂️ Top-Level Directories You Must Know

Here are the most important directories in RHCSA and daily Linux use:

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📚 Key Directories Explained Simply

🛠️ /etc – Configuration Center

Contains all major config files for services and system

Examples:

Copy/etc/hostname       # System name
/etc/hosts          # Manual DNS entries
/etc/ssh/sshd_config # SSH settings
/etc/fstab          # Mount points
/etc/passwd         # User account list

📌 RHCSA Tip: You'll edit files in /etc often (firewalld, sshd, networking, etc.)

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🏠 /home – User Data

Where each regular user stores their files

Examples:

Copy/home/rama         
/home/joko         

📌 RHCSA Tip: Know how to manage /home permissions and backups

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🧾 /var – Variable Data

Stores data that changes over time

Examples:

Copy/var/log/           # System logs (check with `journalctl`)
/var/spool/         # Print jobs or mail
/var/www/           # Web server root (Apache)
/var/lib/           # App databases (like yum, firewalld)

📌 RHCSA Tip: Logs are in /var/log/ — useful for troubleshooting

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🔍 View Filesystem Layout in CLI

Show all mounted filesystems:

Copydf -h

View detailed hierarchy:

Copytree -L 1 /

(Install tree if not available: sudo dnf install tree)

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Bonus: to get location configuration file for 3rd party package

"When I install a 3rd-party package like nginx, where are its config files located?"

Here are 3 reliable ways to find it — just like you mentioned — with examples and best practices.

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🔎 1. Check the Official Documentation

Most 3rd-party tools (like Nginx, Apache, PostgreSQL, etc.) document the default config file location clearly.

For Nginx:

• Docs: https://nginx.org/en/docs/

• Default location (in most distros):

  Copy/etc/nginx/nginx.conf
  

✅ Best Practice:

• Use vendor docs when installing from source or non-default repos.

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📖 2. Use man (Manual Page)

The man page of the service usually mentions config file locations at the top or near the bottom.

Example:

Copyman nginx

Then:

• Press / to search

• Type conf or configuration

• Example output:

  CopyThe default configuration file is /etc/nginx/nginx.conf
  

✅ Works for: nginx, sshd, httpd, postfix, etc.

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🔍 3. Use Linux File Search Tools

A. rpm -ql (for RPM-based systems like RHEL/Rocky)

Lists all files installed by a package:

Copyrpm -ql nginx

Output sample:

Copy/etc/nginx/nginx.conf
/etc/nginx/conf.d/
/usr/sbin/nginx
...

B. dnf repoquery --list (modern way)

Copydnf repoquery --list nginx

C. Use find or locate commands:

Copysudo find /etc -name '*nginx*'

Or faster (after updating database):

Copysudo updatedb
locate nginx.conf

✅ Best for quick searches if unsure where files are stored.

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📦 Bonus: Check Package Info via rpm

To see package ownership of a config file:

Copyrpm -qf /etc/nginx/nginx.conf

To see a short description:

Copyrpm -qi nginx