FHS (Filesystem Hierarchical Standard)

Binaries:

• /bin: Essential user binaries (ls, cp, cat, bash).

• /sbin: Essential system binaries (for root) (fdisk, reboot, ip).

Configuration files:

• /etc: For example, passwd, fstab, hosts.

Variable data:

• /var/log: If a service isn't starting, this is the first place you look. Specifically dmesg or syslog / messages

/mnt vs /media:

• /media is for automatically mounted removable media (CDs, USBs).

• /mnt is for manually mounted temporary filesystems by the administrator.

Virtual systems (exist in memory only, volatile):

• /proc: Reporting on hardware and providing process information (read-only)

• /sys: Hardware inventory and management (status of devices can be modified, writable)

• /dev: Hardware access points (how you talk to hardware). The actual device nodes (files) used to talk to hardware.

• /run: Runtime data since last boot (PID files, sockets)

udev:

The big picture

/sys → udev → /dev

(kernel (the (device

hardware bridge) nodes)

inventory)

What does udev do?

• /sys → udev reads from here to get device information and attributes

• /dev → udev writes to here to create/remove device nodes

Bootloader and kernel files:

• /boot: vmlinuz, initramfs, grub/

User programs, libraries, and docs:

• /usr: /usr/bin, /usr/lib, /usr/share/man

Temporary files:

• /tmp: Cleared on reboot

Personal directories for regular users:

• /home: Documents, local settings

The home directory for the root user:

• /root