Linux File System Hierarchy Explained

January 9, 2026 5 min read Systems Administration

linuxfilesystemdirectoriesbeginner

Linux has a standardized directory structure. Understanding it helps you navigate any Linux system and know where to find (or put) things.

The Root of Everything

Everything starts at / (root). Unlike Windows with drive letters (C:, D:), Linux has a single unified tree.

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

Directory Breakdown

/bin - Essential Binaries

Basic commands needed for single-user mode and system recovery:

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ls /bin
# ls, cp, mv, rm, cat, echo, bash...

/sbin - System Binaries

Administrative commands (typically need root):

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ls /sbin
# fdisk, mkfs, iptables, reboot...

/etc - Configuration Files

System-wide configuration:

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/etc/
├── passwd          # User accounts
├── shadow          # Password hashes
├── group           # Group definitions
├── hosts           # Static hostname mapping
├── fstab           # Filesystem mount table
├── ssh/            # SSH configuration
├── nginx/          # Nginx configuration
└── systemd/        # Systemd units

Remember: /etc = “Editable Text Configuration”

/home - User Home Directories

Each user gets a directory:

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/home/
├── alice/
│   ├── Documents/
│   ├── Downloads/
│   └── .bashrc
└── bob/
    └── ...

Your home is ~ or $HOME.

/root - Root User’s Home

The superuser’s home directory (not in /home):

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/root/
├── .bashrc
└── .ssh/

/var - Variable Data

Data that changes during operation:

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/var/
├── log/            # System and application logs
│   ├── syslog
│   ├── auth.log
│   └── nginx/
├── cache/          # Application caches
├── lib/            # State information
│   ├── docker/
│   └── mysql/
├── mail/           # User mailboxes
├── spool/          # Print queues, cron jobs
└── www/            # Web server files (on some systems)

/tmp - Temporary Files

Temporary storage, often cleared on reboot:

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# Create temp file
mktemp
# /tmp/tmp.Abc123

# Or use for scripts
cp data.txt /tmp/data_backup.txt

/usr - User Programs

Secondary hierarchy for user programs:

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/usr/
├── bin/            # User commands
├── sbin/           # Admin commands
├── lib/            # Libraries
├── local/          # Locally installed software
│   ├── bin/
│   └── lib/
├── share/          # Architecture-independent data
│   ├── doc/
│   └── man/
└── src/            # Source code

Modern note: On many systems, /bin is symlinked to /usr/bin.

/opt - Optional Software

Third-party applications:

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/opt/
├── google/
│   └── chrome/
└── slack/

/dev - Device Files

Hardware and pseudo-devices:

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/dev/
├── sda             # First hard drive
├── sda1            # First partition
├── tty             # Terminals
├── null            # Discard output
├── zero            # Endless zeros
├── random          # Random data
└── urandom         # Non-blocking random

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# Discard output
command > /dev/null

# Create 1MB file of zeros
dd if=/dev/zero of=file.bin bs=1M count=1

/proc - Process Information

Virtual filesystem for kernel and process info:

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/proc/
├── 1/              # Process ID 1 (init)
│   ├── cmdline     # Command line
│   ├── status      # Process status
│   └── fd/         # File descriptors
├── cpuinfo         # CPU information
├── meminfo         # Memory information
├── loadavg         # Load average
└── version         # Kernel version

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# Check CPU
cat /proc/cpuinfo

# Check memory
cat /proc/meminfo

# Check kernel version
cat /proc/version

/sys - System Information

Kernel device and driver info:

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/sys/
├── block/          # Block devices
├── class/          # Device classes
├── devices/        # All devices
└── fs/             # Filesystems

/boot - Boot Files

Kernel and bootloader:

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/boot/
├── vmlinuz-*       # Linux kernel
├── initrd.img-*    # Initial ramdisk
└── grub/           # GRUB bootloader

/lib - Essential Libraries

Libraries for binaries in /bin and /sbin:

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/lib/
├── x86_64-linux-gnu/   # Architecture-specific
├── modules/            # Kernel modules
└── systemd/            # Systemd components

/media and /mnt - Mount Points

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/media/             # Removable media (USB, CD)
├── usb-drive/
└── cdrom/

/mnt/               # Temporary mounts
└── backup-drive/

/srv - Service Data

Data for services provided by the system:

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/srv/
├── www/            # Web server
├── ftp/            # FTP server
└── git/            # Git repositories

/run - Runtime Data

Runtime data since last boot:

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/run/
├── user/           # Per-user runtime
├── lock/           # Lock files
└── docker.sock     # Docker socket

Finding Things

locate - Fast File Search

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# Update database first
sudo updatedb

# Find files
locate nginx.conf

find - Powerful Search

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# Find by name
find /etc -name "*.conf"

# Find by type
find /var/log -type f -name "*.log"

# Find by size
find / -size +100M

which / whereis - Find Commands

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which python
# /usr/bin/python

whereis nginx
# nginx: /usr/sbin/nginx /etc/nginx /usr/share/nginx

Quick Reference

Directory	Purpose
`/`	Root of filesystem
`/bin`	Essential commands
`/etc`	Configuration files
`/home`	User home directories
`/var`	Variable data (logs, cache)
`/tmp`	Temporary files
`/usr`	User programs
`/opt`	Third-party software
`/dev`	Device files
`/proc`	Process information

Understanding this hierarchy makes Linux predictable. Configuration in /etc, logs in /var/log, your stuff in /home. Once you know the pattern, any Linux system feels familiar.