The Linux file system is a structured way of storing and organizing files and directories. Everything in Linux is treated as a file, including documents, directories, devices and even processes.

Linux follows a tree-like structure, starting from a single top-level directory.

1. / (Root Directory):

   —> The root directory is represented by a forward slash (/).

   —> This is the top-level directory in Linux.

   —> We can say that it is the starting point of the Linux File System, means the Linux starts building the system from here.

   —> All other directories and files are located under the root directory.

   —> Without root directory, Linux cannot function.

   Example: /etc, /home, /var all exist under /

   DevOps use:

   • All mounts (EBS, NFS, volumes) attach under /

   • Containers and servers depend on this hierarchy.

   • System recovery starts from root.

     Example: Mounting EBS

2. /bin:

   —> It contains essential user commands.

   —> These commands work even in rescue mode.

   —> Used by all users.

   Example: ls, cp, rm

   DevOps use:

   • CI/CD scripts rely on these commands.

   • Used inside Docker containers.

   • Required in minimal OS images.

     Example: Jenkins job uses

3. /boot:

   —> Stores bootloader and kernel files.

   —> Required during system startup.

   —> Without this, Linux cannot boot.

   Example: /boot/config-5.15.0

   DevOps use:

   • Kernal upgrades during patching.

   • Required for VM reboot after updates.

   • Boot failure troubleshooting.

     Example: Updating kernel in EC2 and rebooting

4. /dev:

   —> Holds device files for hardware.

   —> Devices are treated as files.

   —> Used to communicate with hardware.

   Example: /dev/sda (disk), /dev/null

   DevOps use:

   • Disk attachements in cloud VMs.

   • Used while mounting volumes.

   • Important in storage troubleshooting.

     Example:

       lsblk
     

5. /etc:

   —> Contains system-wide configuration files.

   —> Mostly test-based and editable.

   —> Changes affect the whole system.

   Example: /etc/hosts, /etc/passwd

   DevOps use:

   • Configuration management (Ansible).

   • App config files stored here.

   • Service-level tuning

     Example:

       /etc/nginx/nginx.conf
     

6. /home:

   —> Stores user-specific data.

   —> Each user has a separate directory.

   —> Safe area for personal files.

   Example: /home/vennela/documents

   DevOps use:

   • SSH keys stored here.

   • User-based deployments.

   • Jenkins agent users

     Example:

       /home/ec2-user/.ssh/authorized_keys
     

7. /lib:

   —> Contains shared libraries.

   —> Required by system binaries.

   —> Similar to .dll files in Windows

   Example: libssl.so

   DevOps use:

   • Dependency resolution

   • Container image runtime support

   • Fixing shared library errors

     Example:

     Error: libssl.so not found

8. /opt:

   —> Used for third-party applications.

   —> Keeps external softwares seperate.

   —> Not managed directly by package manager.

   Example: /opt/oracle

   DevOps use:

   • Installing custom applications.

   • Vendor software installations.

   • CI tools setup.

     Example:

       /opt/sonarqube
     

9. /sbin:

   —> Stores system administration commands.

   —> Mainly used by root user.

   —> Helps in system repair and maintenance.

   Example: iptables, shutdown

   DevOps use:

   • Network & service management.

   • Disk repair & system recovery.

   • Used in automation scripts.

     Example:

       iptables -L
     

10. /tmp:

    —> Stores temporary runtime files.

    —> Cleared automatically on reboot.

    —> Used by programs and users.

    Example: Browser temp files

    DevOps use:

    • Build artifacts.

    • CI pipeline temp storage.

    • Script execution files.

      Example:

        /tmp/build-output
      

11. /usr:

    —> Contains user-level applications and tools.

    —> Most software lives here.

    —> Not required for early boot.

    Example: /usr/bin/java, /usr/lib

DevOps use:

• • Installed DevOps tools.

    • Language runtimes.

    • Package-managed software.

      Example:

        /usr/bin/docker
        /usr/bin/kubectl
      

      In conclusion, we can say that understanding the Linux file system helps us know where things live and why they matter. But in DevOps*, this knowledge is essential for configuration, troubleshooting and managing production system efficiently.*