10: OCI ‐ File system structure in Linux - pavankumarchittajallu/OCI_DOC GitHub Wiki

Linux Filesystem Hierarchy Standard (FHS):

1. Understand the Root Directory (/)

• The Linux file system is organized as a single hierarchical tree starting from the root directory, denoted as /.
• All files and directories branch out from this root.
• Think of / as the top-level folder containing all other directories and files on the system.

2. Explore Main Top-Level Directories

Each top-level directory under / has a specific purpose:

Directory	Purpose
/bin	Essential user binaries (commands like ls, cp, mv) available to all users.
/sbin	System binaries used for system administration (e.g., fsck, iptables), typically root-only.
/etc	System-wide configuration files and startup/shutdown scripts.
/home	User home directories containing personal files and settings.
/root	Home directory for the root user (administrator).
/usr	User utilities and applications, including binaries and libraries (/usr/bin, /usr/lib).
/var	Variable data like logs (/var/log), mail, and temporary files.
/tmp	Temporary files, cleared on reboot.
/dev	Device files representing hardware (disks, terminals, USBs).
/proc	Virtual filesystem with process and kernel info.
/sys	Kernel and hardware interface files.
/media	Mount points for removable media (USB drives, CDs).
/mnt	Temporary mount points for filesystems.
/opt	Optional third-party software packages.
/lib and /lib64	Essential shared libraries for binaries in /bin and /sbin.
/boot	Bootloader files and Linux kernel images.
/run	Runtime data like process IDs and locks.
/srv	Data for services like web and FTP servers.

This structure is fairly consistent across Linux distributions due to the Filesystem Hierarchy Standard (FHS).

3. Use Commands to Explore the Structure

• Open a terminal and navigate to the root directory:

  cd /
  

• List top-level directories with details:

  ls -l /
  

4. Learn Navigation Basics

• cd to change directories:
  • cd /etc - go to /etc
  • cd .. - go up one directory
  • cd ~ - go to your home directory
• pwd to print current directory path
• ls to list files and directories
  • ls -a to show hidden files
  • ls -l for detailed info

5. Understand File Types in Linux

• Everything in Linux is a file or a process.
• File types include:
  • Regular files: text, binaries, images, etc.
  • Directories: special files that contain other files.
  • Special files: device files (in /dev), symbolic links, sockets, and pipes.

6. Practical Tips

• Use absolute paths (starting with /) to specify exact locations.
• Use relative paths (from the current directory) for convenience.
• Use tab completion in the terminal to auto-complete file and directory names.
• Use the find command to search files by name or type:

  find /home -name "*.txt"
  

• Use stat to view file metadata (permissions, ownership, timestamps).

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