Explanation of Linux Directory Structure and Important Files Paths

Hello friends,

You know I am a newbie and fan of linux system. Since last 2 years I am using linux for my primary and only OS. Its a real complex system and I am learning this system day by day. For any person, who does not have a sound knowledge of Linux Operating System and Linux File System, dealing with the files and their location, their use may be horrible, and a newbie may really mess up.

This post is aimed to provide the information about Linux File System, some of the important files, their usability and location.

Linux Directory Structure Diagram

A standard Linux distribution follows the directory structure as provided below with Diagram and explanation.

Linux Directory Structure
Linux Directory Structure

Each of the above directory (which is a file, at the first place) contains important information, required for booting to device drivers, configuration files, etc. Describing briefly the purpose of each directory, we are starting hierarchically.

  1. /bin : All the executable binary programs (file) required during booting, repairing, files required to run into single-user-mode, and other important, basic commands viz., cat, du, df, tar, rpm, wc, history, etc.
  2. /boot : Holds important files during boot-up process, including Linux Kernel.
  3. /dev : Contains device files for all the hardware devices on the machine e.g., cdromcpu, etc
  4. /etc : Contains Application’s configuration files, startupshutdownstartstop script for every individual program.
  5. /home : Home directory of the users. Every time a new user is created, a directory in the name of user is created within home directory which contains other directories likeDesktopDownloadsDocuments, etc.
  6. /lib : The Lib directory contains kernel modules and shared library images required to boot the system and run commands in root file system.
  7. /lost+found : This Directory is installed during installation of Linux, useful for recovering files which may be broken due to unexpected shut-down.
  8. /media : Temporary mount directory is created for removable devices viz., media/cdrom.
  9. /mnt : Temporary mount directory for mounting file system.
  10. /opt : Optional is abbreviated as opt. Contains third party application software. Viz., Java, etc.
  11. /proc : A virtual and pseudo file-system which contains information about running process with a particular Process-id aka pid.
  12. /root : This is the home directory of root user and should never be confused with ‘/
  13. /run : This directory is the only clean solution for early-runtime-dir problem.
  14. /sbin : Contains binary executable programs, required by System Administrator, forMaintenance. Viz., iptables, fdisk, ifconfig, swapon, reboot, etc.
  15. /srv : Service is abbreviated as ‘srv‘. This directory contains server specific and service related files.
  16. /sys : Modern Linux distributions include a /sys directory as a virtual filesystem, which stores and allows modification of the devices connected to the system.
  17. /tmp :System’s Temporary Directory, Accessible by users and root. Stores temporary files for user and system, till next boot.
  18. /usr : Contains executable binariesdocumentationsource codelibraries for second level program.
  19. /var : Stands for variable. The contents of this file is expected to grow. This directory contains loglockspoolmail and temp files.

Exploring Important file, their location and their Usability

Linux is a complex system which requires a more complex and efficient way to startstop,maintain and reboot a system unlike Windows. There is a well defined configuration files,binariesman pagesinfo files, etc. for every process in Linux.

  1. /boot/vmlinuz : The Linux Kernel file.
  2. /dev/hda : Device file for the first IDE HDD (Hard Disk Drive)
  3. /dev/hdc : Device file for the IDE Cdrom, commonly
  4. /dev/null : A pseudo device, that don’t exist. Sometime garbage output is redirected to/dev/null, so that it gets lost, forever.
  5. /etc/bashrc : Contains system defaults and aliases used by bash shell.
  6. /etc/crontab : A shell script to run specified commands on a predefined time Interval.
  7. /etc/exports : Information of the file system available on network.
  8. /etc/fstab : Information of Disk Drive and their mount point.
  9. /etc/group : Information of Security Group.
  10. /etc/grub.conf : grub bootloader configuration file.
  11. /etc/init.d : Service startup Script.
  12. /etc/lilo.conf : lilo bootloader configuration file.
  13. /etc/hosts : Information of Ip addresses and corresponding host names.
  14. /etc/hosts.allow : List of hosts allowed to access services on the local machine.
  15. /etc/host.deny : List of hosts denied to access services on the local machine.
  16. /etc/inittab : INIT process and their interaction at various run level.
  17. /etc/issue : Allows to edit the pre-login message.
  18. /etc/modules.conf : Configuration files for system modules.
  19. /etc/motd : motd stands for Message Of The Day, The Message users gets upon login.
  20. /etc/mtab : Currently mounted blocks information.
  21. /etc/passwd : Contains password of system users in a shadow file, a security implementation.
  22. /etc/printcap : Printer Information
  23. /etc/profile : Bash shell defaults
  24. /etc/profile.d : Application script, executed after login.
  25. /etc/rc.d : Information about run level specific script.
  26. /etc/rc.d/init.d : Run Level Initialisation Script.
  27. /etc/resolv.conf : Domain Name Servers (DNS) being used by System.
  28. /etc/securetty : Terminal List, where root login is possible.
  29. /etc/skel : Script that populates new user home directory.
  30. /etc/termcap : An ASCII file that defines the behaviour of Terminalconsole andprinters.
  31. /etc/X11 : Configuration files of X-window System.
  32. /usr/bin : Normal user executable commands.
  33. /usr/bin/X11 : Binaries of X windows System.
  34. /usr/include : Contains include files used by ‘c‘ program.
  35. /usr/share : Shared directories of man filesinfo files, etc.
  36. /usr/lib : Library files which are required during program compilation.
  37. /usr/sbin : Commands for Super User, for System Administration.
  38. /proc/cpuinfo : CPU Information
  39. /proc/filesystems : File-system Information being used currently.
  40. /proc/interrupts : Information about the current interrupts being utilised currently.
  41. /proc/ioports : Contains all the Input/Output addresses used by devices on the server.
  42. /proc/meminfo : Memory Usages Information.
  43. /proc/modules : Currently using kernel module.
  44. /proc/mount : Mounted File-system Information.
  45. /proc/stat : Detailed Statistics of the current System.
  46. /proc/swaps : Swap File Information.
  47. /version : Linux Version Information.
  48. /var/log/lastlog : log of last boot process.
  49. /var/log/messages : log of messages produced by syslog daemon at boot.
  50. /var/log/wtmp : list login time and duration of each user on the system currently.

That’s all for now. Hope this could help a lot of newbie like me. If not then I must say its really help me a lot to know the linux file system.

Hope to see you soon guys 🙂

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