Page 158 - DCAP106_OPERATING_SYSTEM_TOOLS

Unit 9: The File System

z z /usr/local is often a separate mount as well, containing programs specific to the local Notes
system (the /usr might be shared across different systems in large environments).
z z /usr/sbin is, like /usr/bin, a location for executable programs, but just like /bin and
/sbin, /usr/sbin contains programs for system administrative purposes only.

General Locations

Everything else which might be placed on a separate medium are considered as general locations.

z z /home contains the home directories of all the local users.
z z /boot contains the static boot-related files, not actually necessary once the system is booted
(for instance, it includes the bootloader configuration and kernel image).

z z /media contains the mount points for the various detachable storage (like USB disks,
DVDs, ...).
z z /mnt is a location for temporarily mounted media (read: not worth the trouble of defining
them in fstab).
z z /opt contains add-on packages and is usually used to install applications into which are
not provided by your package manager natively (as those should reside in /usr) or build
specific to the local system (/usr/local).
z z /tmp contains temporary files for the system tools. The location can be cleansed at boot up.
z z /var contains data that changes in size, such as log files, caches, etc.

Special Kernel-provided File Systems

Some file system locations are not actually stored on a partition or disk, but are created and
managed on-the-fly by the Linux kernel.

z z /proc contains information about the running system, kernel and processes
z z /sys contains information about the available hardware and kernel tasks

z z /dev nowadays can be provided by the Linux kernel as well, offering a small set of default
device
z z nodes (so that the system can boot until udev is ready to take over control of /dev)

9.2.3 The Root File System /

As we know, the root file system / is considered as the parent of the whole file system. The root
file system / is the first file system that is mounted when the kernel boots, and your system will
not function appropriately if the kernel detects corruption on this file system. Also, due to the
nature of the boot process, this file system will eventually become writeable (as the boot process
needs to store its state information, etc.).
Some root file system locations are strongly advised to remain on the root file system. These
locations are:

z z /bin and /sbin as these contain the binaries (commands) or links to binaries that are needed
to get a system up to the point it can mount other file systems. Although this functionality
is gradually becoming less and less so, it would still break systems if you make separate
mounts for these (small) locations.

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