Linux Directory Structure

Let's learn about the Linux directory structure

References: howtogeek.com, realforce111.tistory.com, coding-factory.tistory.com

Linux Directory Structure Diagram

• Linux is a Unix-based OS, so it uses many parts of Unix as-is

  • In Unix, all system-related information and hardware devices are managed as files

    • Like Unix, Linux also manages system-related information as files!

• Linux uses directories for efficient file management, organized in a Tree structure as shown above

• Directories are categorized by the nature, content, and access permissions of commands

• Most Linux distributions

  • Use FHS (Filesystem Hierarchy Standard), and

  • Store files with the same purpose in the same location, so

    • System resources and programs can be easily found

      • In other words, commands / files / documents are managed in their own separate locations!

Directory Structure

I am currently using Ubuntu 18.04, one of the Linux distros, and the directory structure is as follows

/ - The Root Directory

• The top-level directory

• Must exist when setting up partitions!

• The directory that serves as the reference for absolute paths

/bin - Essential User Binaries

• The directory containing Linux basic commands (binaries)

• Contains the essential commands needed for system operation

• Contains commands required for booting

  • Also contains general commands that system users can use after booting

/boot - Static Boot Files

• The directory containing kernel images and boot information files needed for system booting

• Contains the kernel boot image file specified in /etc/lilo.conf

• A very important directory during booting!

/cdrom - Historical Mount Point for CD-ROMs

• Not included in the FHS standard, but can be found in distros including Ubuntu

• A temporary storage location for CD-ROMs

/dev - Device Files

• The directory where device files are stored

• However, they are not actual files!

  • It is a virtual file system that does not take up physical space

/etc - Configuration Files

• The directory containing system configuration files

  • Network-related configuration files

  • User information / password information

  • File system information

  • Security files

  • System initialization files and other important configuration files are located in this directory

/home - Home Folders

• The location where system user home directories are created

• When a user account is created, a new user directory with the same name as the account is created as a subdirectory under /home!

• Since my Ubuntu only has one user chloe, the /home directory looks like this!

/lib - Essential Shared Libraries

• The directory containing Library files that the binaries in /bin and /sbin folders depend on

  • Libraries that the binaries in /usr/bin depend on are located in /usr/lib!

• Kernel module files exist in /lib/modules

• Most libraries are connected via links

/media - Removable Media

• The directory for connecting external devices such as CD-ROMs and USB drives

/mnt - Temporary Mount Points

• The directory for temporarily mounting file systems

• Generally used when mounting other devices

  • Other directories can also be used!

/opt - Optional Packages

• The directory where additional packages are installed

/proc - Kernel & Process Files

• Stores various processor, program information, and hardware information of the system

• Like the /dev directory, it is a virtual file system that does not have physical capacity!

  • It is not stored on the hard disk, but stored in memory by the kernel

• Shows the current system configuration

• You can check system information by using the cat command on files inside the /proc directory

  • ex) Checking Interrupt information - cat /proc/interrupts

/root - Root Home Directory

• The home directory of the root user

  • Both / directory and /root are called root, but they are different!

/run - Application State Files

• The directory where files related to running services are stored

/sbin - System Administration Binaries

• Similar to the /bin directory, but contains executable commands related to system administration

  • System check and recovery commands

  • System initialization and shutdown commands, and other executable files needed for system administration exist here!

/srv - Service Data

• The directory where data for services provided by the system such as FTP and Web are stored

/tmp - Temporary Files

• Stores temporary data generated during system use

  • Gets cleared during booting!

/usr - User Binaries & Read-Only Data

• Contains most program library files for general users

  • Basic executable files

  • Library files

  • Header files and other files are stored in this directory

/var - Variable Data Files

• The directory where data and logs (operation records) generated during system operation are stored

• Stores dynamic files used by the system

  • Variable data storage directory