Master Linux Filesystem Hierarchy: Where Every Directory Belongs

Linux’s directory layout can be confusing, but understanding the role of each top‑level folder helps you place files correctly and keep the system organized.

/bin

This directory holds essential executable binaries needed during boot, such as ls and top. If /usr/bin is unavailable, /bin may be used as a fallback symlink.

/boot

Contains the kernel, bootloader (e.g., GRUB), and EFI files required to start the operating system. Damage to this directory can prevent the system from booting.

/dev

Short for “device”, it provides references to hardware and virtual devices (hard disks, USB sticks, terminals, null device, etc.). Accessing a device from the command line usually involves a file under /dev.

/etc

Stores all core configuration files for the system and installed applications. Modify files here to change program behavior, network settings, or cron jobs.

/home

Top‑level directory for user home directories. Each user’s personal files—documents, music, pictures—belong here, accessed via ~. Shared program configuration or system data should not be placed in /home.

/lib, /lib32, /lib64, …

Contain shared C libraries and kernel modules required by binaries in /bin and /sbin. Architecture‑specific libraries reside in the corresponding lib subdirectory.

/lost+found

Used by the filesystem to store recovered fragments of corrupted files after crashes or hardware failures.

/media

Mount point for removable media such as CDs, USB drives, or ISO images. Historically also used for floppy and Zip disks.

/mnt

A generic mount point for temporarily mounting external disks, NFS shares, or other filesystems.

/opt

Originally intended for optional third‑party software packages that are not part of the base distribution. Many distributions still use it for large, self‑contained applications.

/proc

A virtual filesystem exposing kernel and process information. Files here are not real data but interfaces to view metrics such as memory usage, process IDs, and system configuration.

/root

Home directory of the root (superuser) account. It resides at /root instead of /home/root for security reasons.

/run

Holds runtime data such as PID files, lock files, and sockets. It is cleared on reboot and is not meant for persistent storage.

/sbin

Contains system binaries used for administrative tasks (e.g., fdisk, usermod). Unlike /bin, these are typically not needed by regular users.

/srv

Intended for data served by the system, such as web server files, FTP data, or other service‑specific resources.

/sys

Similar to /proc, it provides structured information about devices and kernel subsystems, depending on the distribution.

/tmp

Temporary storage for files that do not need to survive a reboot. The system may clean this directory automatically.

/usr

Described by the FHS as “shareable, read‑only data”. It can be mounted read‑only on other systems. In practice it holds architecture‑independent data, libraries, and user‑installed software (e.g., /usr/share, /usr/local).

/var

Stores variable data that changes at runtime: printer spools, lock files, package caches, email, logs, etc. Subdirectory /var/local is often used for miscellaneous configuration files.

Understanding these directories and their intended contents makes the Linux filesystem intuitive and helps you maintain a clean, well‑organized system.