Skip to content

05.Linux_File_Hierarchy.md

Latest commit

 

History

History
178 lines (134 loc) · 4.76 KB

05.Linux_File_Hierarchy.md

File metadata and controls

178 lines (134 loc) · 4.76 KB

Linux Directory Structure

/tmp Directory

"tmp" stands for "temporary."

  • The /tmp directory contains temporary files created during the current session.
  • It is used for files needed only temporarily and is automatically cleared upon system shutdown.
  • Note: Not recommended for storing permanent files.

Example Commands

  1. Creating and Editing a Temporary File

    gedit demo.txt
    • Open demo.txt and add content.

  2. Viewing Content in demo.txt

    cat demo.txt
    • Displays the content of demo.txt: 
      add some content here
add more extra content here

  3. Checking File Permissions

    ls -l demo.txt
    • Example Output: 
      -rw-rw-r-- 1 akshay akshay 49 Sep 4 16:20 demo.txt

  4. Modifying File Permissions

    chmod u-rw demo.txt
    • Removes read and write permissions for the user, resulting in permission denial when trying to read: 
      cat demo.txt
# Output: cat: demo.txt: Permission denied

  5. Restoring Permissions

    chmod u+rw demo.txt
    • Grants read and write permissions back to the user.

  6. Appending Content

    cat >> demo.txt
added last line by akshay
    • Use Ctrl + D to save and exit.

/dev Directory

"dev" stands for "device."

  • In Linux, all devices are represented as files.
  • The /dev directory contains special files used to interact with devices.

Common Files

  • tty: Terminal-related file.
  • fd: Floppy drive-related file.
  • hd: Hard disk-related file.
  • ram: RAM-related file.
  • stdin: Standard input (keyboard).
  • stdout: Standard output (terminal/monitor).
  • stderr: Standard error output (terminal/monitor).

/mnt Directory

"mnt" stands for "mount."

  • The /mnt directory is used for attaching external file systems to the Linux file system (e.g., pen drives, CDs, external hard disks).
  • Mounting: Process of attaching external file systems. Older OS versions required manual mounting; recent OS versions do this automatically.

/media Directory

  • This directory is used for automatically mounted devices (e.g., USB drives, external hard drives, CD/DVD drives).
  • Difference from /mnt:
    • /mnt: Contains manually mounted files.
    • /media: Contains automatically mounted files.

/opt Directory

"opt" stands for "optional."

  • Contains installation files for third-party software not included in the default system installation.
  • Examples:
    • Google Chrome
    • Oracle products
    • Other manually installed applications

/lib Directory

  • The /lib directory stores essential shared libraries and kernel modules required by the Linux OS, commands, and applications.

/var Directory

"var" stands for "variable data."

  • Stores data that frequently changes, like system logs, mail spools, and print spools.
  • Example: Log files are commonly stored here.

/home Directory

  • Each user has a unique directory within /home to store personal files.
  • Example: /home/durgasoft contains folders like Desktop, Downloads, Movies, Pictures.

/proc Directory

"proc" stands for "processes."

  • Contains information about all running processes.

  • Each process has a directory named after its Process ID (PID) to store specific process data.

  • Note: Use ps command to view running processes.

    Example Command

    ps -ef
    • Displays all processes in full format.

/root Directory

The home directory for the superuser.

  • Located at /root in the filesystem.

  • Not to be confused with / (root directory for the entire filesystem).

    Note

    • /home/durgasoft - User Home Directory for durgasoft
    • /root - Super User Home Directory

Difference Between / and /root

  • / is the topmost directory in the Linux file system.
  • /root is a subdirectory of /, serving as the home directory for the superuser.

/boot Directory

  • Contains files required to boot the Linux operating system, such as the kernel, initial RAM disk, and bootloader configuration.

/usr Directory

"usr" stands for "user."

  • Contains user-related software and applications.
  • Subdirectories:
    • /usr/bin: User commands.
    • /usr/sbin: System administration commands.
    • /usr/lib: Libraries.
    • /usr/share: Architecture-independent data.
  • Note: Historically, "usr" stood for "Unix System Resources," though it is now commonly interpreted as "user."

Additional Notes on Linux File System

  • Main Advantage: The Linux file system structure allows the OS to easily locate files.
  • File System Naming:
    • Linux Examples: ext2, ext3, ext4, XFS
    • Windows Examples: NTFS, FAT