The Filesystem Hierarchy

Linux presents all storage as a single tree rooted at /, with standardized directories for standardized purposes - the Filesystem Hierarchy Standard (FHS) defines what goes where.

Fundamentals Updated August 28, 2026

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Unlike Windows' per-drive letters, Linux has exactly one directory tree, rooted at /. Every disk, partition, network share, or removable device gets attached (mounted) somewhere within that tree rather than getting its own top-level namespace - see Mounting and fstab for how that attachment works.

Most distributions follow the Filesystem Hierarchy Standard (FHS) for where things live, though adherence varies slightly by distro and has loosened somewhat with newer conventions like /usr merges.

The directories that matter most

Path Purpose
/bin, /usr/bin Executable programs. On most modern distros /bin is a symlink into /usr/bin (the "usr merge").
/etc System-wide configuration files, almost always plain text.
/home Personal directories for regular users (/home/alice).
/root The root user's home directory - deliberately outside /home.
/var Data that changes at runtime: logs (/var/log), spool files, caches.
/tmp Temporary files, typically cleared on reboot.
/opt Self-contained third-party software packages.
/proc A virtual filesystem exposing kernel and process information - see below.
/sys A virtual filesystem exposing kernel and device state, used for hardware configuration.
/dev Device files representing hardware (/dev/sda, /dev/null).
/mnt, /media Conventional mount points for manual and removable media mounts, respectively.

/proc and /sys aren't real files

Both are virtual filesystems generated by the kernel on the fly - nothing under them exists on disk. Reading them queries live kernel state:

cat /proc/cpuinfo | grep "model name" | head -1

model name      : AMD Ryzen 9 7950X 16-Core Processor

cat /proc/uptime

128453.21 42011.83

(The first number is seconds since boot; the second is total idle time across all cores.) /sys is used more often for writing - toggling device settings - while /proc is read more often for inspection. Each process also gets its own subdirectory under /proc/<pid>/, which is how tools like ps and top get their data. See Process Lifecycle.

Finding your way around

tree -L 1 -d /

/
├── bin -> usr/bin
├── boot
├── dev
├── etc
├── home
├── lib -> usr/lib
├── mnt
├── opt
├── proc
├── root
├── run
├── srv
├── sys
├── tmp
├── usr
└── var

If a distro's layout looks unfamiliar, man hier (available on most systems) documents the FHS conventions that distro claims to follow.