The directory structure of Linux explained

The directory structure of Linux is organized in a hierarchical tree-like format, with the root directory (/) at the base. Each directory serves a specific purpose and contains specific types of files. Here's an overview of the common directories found in a typical Linux file system and their significance, along with some examples:

Root Directory (/)

The root directory is the top-level directory in the Linux file system. All other directories and files are contained within this directory.

/bin

• Purpose: Contains essential binary executables for system operation.
• Significance: Programs in /bin are necessary for booting and repairing a system.
• Example: /bin/ls (list directory contents), /bin/cp (copy files), /bin/mkdir (create directories).

/boot

• Purpose: Contains files necessary for the booting process.
• Significance: Includes the Linux kernel and boot loader configuration files.
• Example: /boot/vmlinuz (compressed Linux kernel image), /boot/grub/grub.cfg (GRUB boot loader configuration).

/dev

• Purpose: Contains device files.
• Significance: Provides an interface to hardware devices (e.g., disks, terminals) through special files.
• Example: /dev/sda1 (first partition on the first SCSI disk), /dev/tty (current terminal).

/etc

• Purpose: Contains system-wide configuration files.
• Significance: Config files for system services and applications are stored here.
• Example: /etc/fstab (file system mount table), /etc/passwd (user account information), /etc/ssh/sshd_config (SSH server configuration).

/home

• Purpose: Contains personal directories for users.
• Significance: Each user has a subdirectory in /home where personal files and settings are stored.
• Example: /home/user1 (home directory for user1), /home/user2 (home directory for user2).

/lib

• Purpose: Contains essential shared libraries and kernel modules.
• Significance: Libraries required by the binaries in /bin and /sbin.
• Example: /lib/libc.so.6 (GNU C Library), /lib/modules (kernel modules).

/media

• Purpose: Mount points for removable media.
• Significance: Used for automatically mounting external devices like USB drives and CDs.
• Example: /media/cdrom (mount point for CD-ROM), /media/usb (mount point for USB drive).

/mnt

• Purpose: Temporarily mounted file systems.
• Significance: Used for manually mounting external devices.
• Example: /mnt/backup (temporary mount point for a backup drive).

/opt

• Purpose: Optional application software packages.
• Significance: Used for installing additional software.
• Example: /opt/google/chrome (Google Chrome installation).

/proc

• Purpose: Contains virtual files that provide information about the system and running processes.
• Significance: Used for system and process information.
• Example: /proc/cpuinfo (CPU information), /proc/meminfo (memory information).

/root

• Purpose: Home directory for the root user.
• Significance: The root user's personal files and settings are stored here.
• Example: /root/.bashrc (bash configuration for root).

/run

• Purpose: Stores transient files needed by system processes.
• Significance: Contains runtime data, typically created at system boot and destroyed at shutdown.
• Example: /run/lock (lock files), /run/user (runtime data for user sessions).

/sbin

• Purpose: Contains essential system binaries.
• Significance: Programs in /sbin are intended for use by the superuser (root).
• Example: /sbin/ifconfig (network interface configuration), /sbin/reboot (reboot the system).

/srv

• Purpose: Contains data for services provided by the system.
• Significance: Used by servers to store data served to users.
• Example: /srv/ftp (files for FTP server), /srv/www (web server files).

/tmp

• Purpose: Contains temporary files.
• Significance: Used by applications to store transient data.
• Example: /tmp/sess_abcdef (temporary session file).

/usr

• Purpose: Contains user programs and data.
• Significance: A secondary hierarchy for read-only data, typically large applications and utilities.
• Example: /usr/bin (user binaries), /usr/lib (user libraries), /usr/share (shared data).

/var

• Purpose: Contains variable data files.
• Significance: Files that are expected to grow in size, such as logs and spool files.
• Example: /var/log (log files), /var/spool (spooled files like mail and print jobs), /var/www (web server files).

Examples of Directory Usage

• Checking Disk Usage:

  du -h /var/log
  

  This command checks the disk usage of log files stored in /var/log.

• Accessing Configuration Files:

  cat /etc/fstab
  

  This command displays the file system table configuration in /etc/fstab.

• Viewing System Information:

  cat /proc/cpuinfo
  

  This command displays CPU information stored in /proc/cpuinfo.