Linux Folders Structure: A Guide to Standard Folder Structure in Linux

Linux is an open-source operating system that is widely used in various industries and by millions of users around the world. One of the key aspects of Linux is its folder structure, which plays a crucial role in organizing and managing files and directories. Understanding the standard folder structure in Linux is essential for both beginners and experienced users, as it provides a solid foundation for navigating and working with the operating system.

In this comprehensive guide, we will explore the standard folder structure in Linux, highlighting the purpose and significance of each directory. Whether you are a system administrator, developer, or simply a Linux enthusiast, this article will serve as a valuable resource to deepen your understanding of Linux and enhance your proficiency in working with the operating system.

1. / – Root directory

The root directory is the top-level directory in the Linux file system hierarchy. It serves as the parent directory for all other directories and files in the system. The root directory is represented by a forward slash (/) and is the starting point for navigating the file system. All other directories and files are located within the root directory or its subdirectories.

The root directory contains essential system files and directories, such as /bin, /boot, /dev, /etc, /home, /lib, /media, /mnt, /opt, /proc, /root, /run, /sbin, /srv, /sys, /tmp, /usr, and /var. These directories play a crucial role in the functioning of the Linux operating system and serve specific purposes in organizing and managing system resources.

2. /bin – Essential user binaries

The /bin directory contains essential user binaries, which are executable files that are necessary for basic system operations. These binaries are accessible to all users and are typically used for common tasks and commands. Examples of binaries found in the /bin directory include ls (list files and directories), cp (copy files), and rm (remove files).

The /bin directory is an essential part of the Linux file system and is included in the system’s default PATH variable, which allows users to execute commands from any directory without specifying the full path to the binary. This directory is crucial for the functioning of the system and should not be modified or deleted.

3. /boot – Boot loader files

The /boot directory contains boot loader files, which are necessary for the system to boot and load the operating system. These files include the kernel, initial RAM disk (initrd), and boot configuration files. The boot loader is responsible for initializing the system and loading the kernel into memory.

When the system starts up, the boot loader is executed, and it allows the user to choose the operating system to boot if multiple operating systems are installed. The /boot directory is typically located on a separate partition and is essential for the proper functioning of the system.

4. /dev – Device files

The /dev directory contains device files, which represent physical and virtual devices connected to the system. In Linux, everything is treated as a file, including devices such as hard drives, USB drives, printers, and network interfaces. Device files allow the system to communicate with and control these devices.

Device files in the /dev directory are organized into subdirectories based on the type of device. For example, /dev/sda represents the first SATA hard drive, /dev/ttyUSB0 represents the first USB serial port, and /dev/null represents a special file that discards any data written to it.

5. /etc – Configuration files

The /etc directory contains configuration files for the system and various applications. These files store settings and parameters that determine the behavior and functionality of the system and applications. The /etc directory is often referred to as the “etcetera” directory, as it contains miscellaneous files that do not fit into other directories.

Configuration files in the /etc directory are typically plain text files that can be edited using a text editor. Examples of configuration files include /etc/passwd (user account information), /etc/hosts (mapping of hostnames to IP addresses), and /etc/resolv.conf (DNS resolver configuration).

6. /home – User home directories

The /home directory contains user home directories, which are personal directories for each user on the system. Each user is assigned a unique home directory, where they can store their personal files, documents, and settings. The home directory is the default location where users are placed when they log in to the system.

By default, user home directories are named after the username and are located within the /home directory. For example, the home directory for the user “john” would be /home/john. The /home directory provides a centralized location for users to store their files and allows for easy management of user accounts.

7. /lib – System libraries

The /lib directory contains system libraries, which are collections of precompiled code that provide essential functions and features to applications and the operating system. System libraries are shared by multiple programs and are loaded into memory when needed.

System libraries in the /lib directory are organized into subdirectories based on the architecture and version of the system. For example, /lib/x86_64-linux-gnu contains libraries for 64-bit systems running on the x86 architecture. System libraries are crucial for the proper functioning of applications and the operating system.

8. /media – Mount point for removable media

The /media directory serves as a mount point for removable media, such as USB drives, optical discs, and external hard drives. When a removable media device is connected to the system, it is automatically mounted to a directory within the /media directory.

Mounted media devices appear as subdirectories within the /media directory, allowing users to access and interact with the files and data stored on the media. For example, a USB drive may be mounted to /media/usb, and an optical disc may be mounted to /media/cdrom.

9. /mnt – Mount point for temporary file systems

The /mnt directory serves as a mount point for temporary file systems. Temporary file systems are file systems that are mounted temporarily and are not permanently attached to the system. These file systems are often used for testing, experimentation, or temporary storage.

When a temporary file system is mounted, it appears as a subdirectory within the /mnt directory. The /mnt directory provides a convenient location for mounting and accessing temporary file systems, allowing users to easily manage and work with these file systems.

10. /opt – Optional software packages

The /opt directory is used for optional software packages that are not part of the core system. Optional software packages are typically installed by the user or system administrator and are not included in the default installation of the operating system.

Software packages installed in the /opt directory are organized into subdirectories based on the package name or vendor. For example, a software package called “example” may be installed in /opt/example. The /opt directory provides a dedicated location for optional software packages, allowing for easy management and separation from the core system files.

11. /proc – Process information pseudo-filesystem

The /proc directory is a special pseudo-filesystem that provides information about running processes and system resources. It does not contain actual files but rather virtual files that represent system information. The /proc directory is dynamically generated and updated in real-time.

Each directory and file in the /proc directory represents a specific process or system resource. For example, /proc/cpuinfo provides information about the system’s CPU, /proc/meminfo provides information about memory usage, and /proc/self represents the current process.

12. /root – Home directory for the root user

The /root directory is the home directory for the root user, which is the superuser or administrator account in Linux. The root user has full privileges and can perform any action on the system. The /root directory is similar to the /home directory but is specific to the root user.

The /root directory is the default location where the root user’s personal files and settings are stored. It provides a separate and secure location for the root user to work and manage the system. Only the root user has access to the /root directory.

13. /run – Runtime variable data

The /run directory contains runtime variable data, which is data that is specific to the current session or runtime of the system. This data is typically created and used by system services and daemons during the system’s operation.

The /run directory is a temporary file system that is created and mounted at boot time. It provides a location for system services to store and access runtime data, such as process IDs (PIDs), socket files, and lock files. The /run directory is cleared and recreated on each system boot.

14. /sbin – System binaries

The /sbin directory contains system binaries, which are executable files that are used for system administration and maintenance tasks. System binaries in the /sbin directory are typically executed by the root user or system services and are not accessible to regular users.

Examples of system binaries found in the /sbin directory include fdisk (disk partitioning), ifconfig (network interface configuration), and init (system initialization). The /sbin directory is essential for system administration and should not be modified or deleted.

15. /srv – Service data

The /srv directory is used for service data, which is data that is specific to a particular service or application running on the system. Service data includes files and directories that are required for the operation of the service.

Service data in the /srv directory is organized into subdirectories based on the service or application. For example, a web server may store its website files in /srv/www, and a file server may store its shared files in /srv/samba. The /srv directory provides a dedicated location for service data, allowing for easy management and separation from other system files.

16. /sys – Sysfs virtual file system

The /sys directory is a virtual file system that provides information about the system’s hardware devices and their configuration. It is a representation of the system’s device tree and allows users and applications to interact with and configure hardware devices.

The /sys directory contains directories and files that represent various hardware devices and their properties. For example, /sys/class/net contains directories for network interfaces, and /sys/block contains directories for block devices such as hard drives. The /sys directory is essential for device management and configuration.

17. /tmp – Temporary files

The /tmp directory is used for temporary files that are created and used by applications and users. Temporary files are typically created during the execution of a program and are meant to be used for a short period of time.

The /tmp directory is accessible to all users and allows for easy sharing of temporary files. However, files in the /tmp directory are not preserved between system reboots and are automatically deleted after a certain period of time or when the system is restarted.

18. /usr – User programs and data

The /usr directory contains user programs and data, including applications, libraries, documentation, and other resources. It is one of the largest directories in the Linux file system and is typically read-only, meaning that it contains files that are not modified during normal system operation.

The /usr directory is organized into subdirectories based on the purpose and type of files. For example, /usr/bin contains user binaries, /usr/lib contains libraries, and /usr/share contains shared data used by multiple applications. The /usr directory is essential for user programs and data.

19. /var – Variable data

The /var directory contains variable data, which is data that changes frequently during the system’s operation. Variable data includes log files, spool files, temporary files, and other data that is specific to the current state of the system.

The /var directory is organized into subdirectories based on the type of data. For example, /var/log contains log files, /var/mail contains user mailbox files, and /var/spool contains application spool files. The /var directory is essential for managing and monitoring system resources.

20. /var/log – Log files

The /var/log directory contains log files, which are records of events and activities that occur on the system. Log files are generated by various system services, applications, and utilities and are used for troubleshooting, monitoring, and auditing purposes.

Log files in the /var/log directory are organized into subdirectories based on the source or type of logs. For example, /var/log/syslog contains system log messages, /var/log/auth.log contains authentication-related logs, and /var/log/apache2 contains logs for the Apache web server. The /var/log directory is essential for system administration and troubleshooting.

21. /var/mail – User mailbox files

The /var/mail directory contains user mailbox files, which are used for storing incoming email messages for each user on the system. When an email is received, it is delivered to the recipient’s mailbox file in the /var/mail directory.

Each user’s mailbox file is named after their username and contains their email messages. Users can access their mailbox files using email clients or command-line utilities. The /var/mail directory is essential for email management and communication.

22. /var/spool – Application spool files

The /var/spool directory contains application spool files, which are temporary files used by applications for various purposes. Spool files are typically used for queuing and processing tasks that require sequential or batch processing.

Examples of spool files found in the /var/spool directory include print spool files, where print jobs are stored before being sent to the printer, and mail spool files, where outgoing email messages are stored before being sent. The /var/spool directory is essential for managing and processing application tasks.

23. /var/www – Web server files (default location)

The /var/www directory is the default location for web server files in Linux. It is used by web servers, such as Apache or Nginx, to store website files, HTML documents, scripts, and other web-related resources.

When a web server is installed, it is typically configured to serve files from the /var/www directory. Web developers and administrators can place their website files in this directory to make them accessible over the internet. The /var/www directory is essential for web server administration and hosting.

24. /var/lib – Variable state information

The /var/lib directory contains variable state information, which is data that changes during the system’s operation and is specific to a particular application or service. Variable state information includes databases, caches, and other data that is used by applications to store their state.

Applications and services create subdirectories within the /var/lib directory to store their data. For example, a database server may store its database files in /var/lib/mysql, and a package manager may store its package database in /var/lib/dpkg. The /var/lib directory is essential for managing and persisting application data.

25. /var/cache – Cache files

The /var/cache directory contains cache files, which are temporary files used by applications to store frequently accessed data. Cache files are used to improve performance by reducing the need to fetch data from slower storage devices, such as hard drives or the network.

Cache files in the /var/cache directory are typically created and managed by system services and applications. Examples of cache files include package caches used by package managers and web browser caches used to store web page data. The /var/cache directory is essential for optimizing system performance.

26. /var/run – Runtime data for system services

The /var/run directory contains runtime data for system services, which is data that is specific to the current session or runtime of the system. This data is typically created and used by system services and daemons during the system’s operation.

The /var/run directory is similar to the /run directory but is specific to system services. It provides a location for system services to store and access runtime data, such as process IDs (PIDs), socket files, and lock files. The /var/run directory is cleared and recreated on each system boot.

27. /var/tmp – Temporary files preserved between system reboots

The /var/tmp directory is used for temporary files that are preserved between system reboots. Unlike the /tmp directory, files in the /var/tmp directory are not automatically deleted and are meant to persist across system restarts.

The /var/tmp directory is accessible to all users and allows for the storage of temporary files that need to be preserved for an extended period of time. However, it is important to regularly clean up the /var/tmp directory to prevent it from filling up with unnecessary files.

In conclusion, understanding the standard folder structure in Linux is essential for navigating and working with the operating system. Each directory serves a specific purpose and plays a crucial role in organizing and managing system resources. By familiarizing yourself with the Linux folder structure, you can enhance your proficiency in Linux and effectively manage your files and directories.

Frequently Asked Questions

1. Can I modify or delete the /bin directory in Linux?

No, you should not modify or delete the /bin directory in Linux. The /bin directory contains essential user binaries that are necessary for basic system operations. Modifying or deleting files in the /bin directory can cause system instability or prevent the system from functioning properly.

2. What is the purpose of the /var/log directory?

The /var/log directory in Linux is used to store log files, which are records of events and activities that occur on the system. Log files are generated by various system services, applications, and utilities and are used for troubleshooting, monitoring, and auditing purposes. The /var/log directory is essential for system administration and troubleshooting.

3. How can I access my user home directory in Linux?

Your user home directory in Linux is located in the /home directory. To access your user home directory, you can use the tilde (~) symbol followed by your username. For example, if your username is “john”, you can access your home directory by typing “cd ~” in the terminal.