Master the 🐧 Linux Filesystem: Inspect /boot, /etc, /dev, /var and More
If you really want to understand a system running on Linux, you don’t always need fancy tools.
Sometimes… all you need is curiosity and the filesystem.
Linux follows a powerful philosophy: “everything is a file.” And once you start hunting through these files, you begin to uncover how the entire system works — from booting to networking to running processes.
Let’s explore what that actually looks like 👇
🌳 The Root of Everything: /
Every Linux system starts from a single root directory:
/
From here, everything branches out into well-defined directories following the Filesystem Hierarchy Standard (FHS).
Some of the most important ones:
/boot→ Kernel & bootloader files/etc→ Configuration files/dev→ Device files/usr→ Installed programs/var→ Logs and runtime data/home→ User directories
Think of this as the map of the system.
⚙️ /etc — The Control Room
If Linux had a “settings panel,” it would be /etc.
This directory controls how your system behaves.
Some key files:
/etc/hostname→ System name/etc/hosts→ Local DNS mappings/etc/resolv.conf→ DNS servers/etc/fstab→ Disk mount configuration/etc/ssh/sshd_config→ SSH settings
👉 The powerful part? These are just plain text files.
Edit them → reboot or reload → behavior changes.
That’s it.
🌐 Networking Through Files
You don’t need ifconfig or ip commands to understand networking.
Linux exposes everything via files:
/proc/net/route→ Routing table/proc/net/arp→ ARP cache/sys/class/net/→ Interface details
Want to check your gateway? Just read /proc/net/route.
Want MAC address? Check /sys/class/net/eth0/address.
👉 It’s like debugging the network by reading files.
🔍 /proc — The Live System Mirror
This is where things get interesting.
/proc is a virtual filesystem that shows the current state of the system.
Each running process gets its own directory:
/proc/<pid>/
Inside you’ll find:
cmdline→ How the process startedexe→ Executable pathfd/→ Open filesenviron→ Environment variables
Example:
/proc/cpuinfo→ CPU details/proc/meminfo→ Memory usage
👉 Tools like ps literally read from /proc behind the scenes.
So when you explore /proc, you're basically talking directly to the kernel.
🧩 /sys and /dev — Hardware in Action
Linux doesn’t hide hardware—it exposes it.
/sys → Hardware View
Shows devices, drivers, and system components
Example:
/sys/class/net/→ Network devices
/dev → Device Access
/dev/sda→ Hard disk/dev/null→ Black hole for data 😄/dev/random→ Random generator
👉 Plug in a USB → a new file appears in /dev.
That’s Linux saying: “Here’s your device.”
🚀 /boot — Where It All Begins
This directory holds everything needed to start the system:
vmlinuz→ Linux kernelinitrd/initramfs→ Temporary root filesystemgrub→ Bootloader configs
The system loads these during startup to bring everything to life.
👉 Want to know which kernel you’re using? Check /boot.
📜 /var/log — The System’s Memory
If something goes wrong, logs tell the story.
Important files:
/var/log/syslog→ General logs/var/log/auth.log→ Login attempts/var/log/kern.log→ Kernel messages
Modern systems also use journald for structured logs.
👉 Debugging tip: Logs are often the first place to look.
👤 Users, Permissions & Security
Linux security is deeply tied to files:
/etc/passwd→ User accounts/etc/shadow→ Password hashes/etc/sudoers→ Admin privileges
And permissions matter:
/tmp→1777(sticky bit)passwdcommand → SUID enabled
👉 Example:
-rwsr-xr-x
That s means the program runs with elevated privileges.
🧠 The Big Insight
After exploring all this, one thing becomes clear:
The Linux filesystem is not just storage — it is the system.
/etc→ Defines behavior/proc&/sys→ Show live state/var/log→ Records history
You don’t always need tools.
Sometimes, just:
cat
less
grep
…is enough to understand everything.
🚀 Final Thoughts
“Filesystem hunting” is one of the most underrated skills in Linux.
It teaches you to:
Think like the system
Debug without tools
Understand deeply, not just operate
And once you get comfortable with it…
👉 You stop using Linux 👉 And start understanding Linux
