Linux Filesystem Hierarchy

Navigating Linux for the first time can feel overwhelming: where do files go, what do all those directories mean, and how does the system keep it all organized? Whether you're tinkering with your first Linux installation or optimizing a seasoned server, understanding the filesystem layout is key to mastering your workflow.

1. /bin — Essential User Binaries

• Contains basic command-line tools required by all users.
• Examples: ls, cat, cp, mv, vim, gzip, curl
• These commands are available even in single-user mode when no other filesystems are mounted.

2. /sbin — System Binaries

• Includes commands used for system administration (requires root access).
• Examples: mount, reboot, fdisk, deluser

3. /lib — Shared Libraries

• Stores essential shared libraries and kernel modules used by /bin and /sbin.
• Think of it as the Linux version of Windows .dll files.
• Example: /lib/x86_64-linux-gnu/libc.so.6

4. /usr — User Programs and Data

• Contains user-related applications and non-essential binaries.
• Subdirectories:
  • /usr/bin → User commands
  • /usr/sbin → System binaries
  • /usr/lib → Libraries for /usr/bin and /usr/sbin

5. /usr/local — Locally Installed Software

• Used for software compiled or installed manually by the user.
• Keeps them separate from system-managed packages.
• Example: /usr/local/bin, /usr/local/lib

6. $PATH — Environment Variable

• Defines directories where the shell looks for executables.
• View it with: echo $PATH
• Example: /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin

7. which — Locate a Command

• Displays the path of the executable being run.
• Example: which ls → /bin/ls

8. /etc — Configuration Files

• Holds system-wide configuration files.
• Examples: /etc/passwd, /etc/hosts, /etc/fstab, /etc/ssh/sshd_config

9. /home — User Home Directories

• Each user has their own directory here.
• Examples: /home/sehran, /home/adnan
• Shortcut: ~ points to your home directory.

10. /boot — Boot Loader Files

• Contains files required to boot the Linux kernel.
• Includes the kernel image, initial RAM disk, and bootloader configurations (like GRUB).
• Examples: /boot/vmlinuz, /boot/initrd.img, /boot/grub/grub.cfg

11. /dev — Device Files

• Represents hardware devices as files.
• Examples:
  • /dev/sda → Hard disk
  • /dev/tty → Terminal
  • /dev/null → Data sink

12. /opt — Optional or Third-Party Software

• Used for optional or vendor-installed applications.
• Example: /opt/google/chrome/

13. /var — Variable Data Files

• Contains data that changes frequently, like logs or cache.
• Subdirectories:
  • /var/log → System logs
  • /var/cache → Cached data
  • /var/spool → Pending tasks

14. /tmp — Temporary Files

• Used to store temporary data.
• Files here are usually deleted on reboot.

15. /proc — Process Information

• A virtual filesystem in memory that provides real-time info about the kernel and running processes.
• Examples:
  • /proc/cpuinfo → CPU details
  • /proc/meminfo → Memory info
  • /proc/1/ → Process with PID 1

Conclusion

The Linux filesystem is like a living map of your system every file, device, and process has its place. Once you understand this hierarchy, navigating and troubleshooting Linux becomes far easier. 🧭🐧