This is a lot to remember, especially at first. For reference, there is a man
page for the Linux file system hierarchy:Click here to view code image
matthew@seymour:~$ man hier
This returns a detailed listing, with a description of each part.
More information about file systems is available in Chapter 21,
“Performance Tuning.”Some of the important directories in Table 10.1, such as those containing user
and root commands or system configuration files, are discussed in the
following sections. You may use and edit files under these directories when
you use Ubuntu.
Essential Commands in /bin and /sbin
The /bin directory contains essential commands used by the system for
running and booting the system. In general, only the root operator uses the
commands in the /sbin directory. The software in both locations is essential
to the system; it makes the system what it is, and changing or removing this
software could cause instability or a complete system failure. Often, the
commands in these two directories are statically linked, which means the
commands do not depend on software libraries residing under the /lib or
/usr/lib directories. Nearly all the other applications on your system are
dynamically linked, meaning that they require the use of external software
libraries (also known as shared libraries) to run. This is a feature for both sets
of software.
The commands in /bin and /sbin are kept stable to maintain foundational
system integrity and do not need to be updated often, if at all. For the security
of the system, these commands are kept in a separate location and isolated so
that changes are more difficult and so it will be more obvious to the system
administrator if unauthorized changes are attempted or made.
Application software changes more frequently, and applications often use the
same functions that other pieces of application software use. This was the
genesis of shared libraries. When a security update is needed for something
that is used by more than one program, it has to be updated in only one
location, a specific software library. This enables easy and quick security
updates that will affect several pieces of non-system-essential software at the
same time by updating one shared library, contained in one file on the
computer.