What's inside the Root Directory (Linux)

/home

/home is where users keep their personal work. In general, this is the only place users are allowed to write files. This keeps things nice and clean.

/usr/share/X11

Support files for the X Windows system

/dev

The /dev directory is a special directory, since it doesn't really contain files in the usual sense. Rather, it contains devices that are available to the system. In Linux, devices are treated like files. You can read and write devices as thought they were files. For example /dev/fd0 is the first floppy disk drive, /dev/sda is the first IDE hard drive. All the devices that the kernel understands are represented here.

/etc

The /etc directory contains the configuration files for the system. All the files in /etc should be text files.

/proc

The /proc directory is special. This directory doesn't contain files. In fact, this directory does not really exist at all. It is entirely virtual. The /proc directory contains little peep holes in the kernel itself. There are a group of numbered entries in this directory that correspond to all the processes running on the system. In addition, there are a number of named entries that permit access to the current configuration of the system. Many of these entries can be viewed.

/usr

The /usr directory contains a variety of things that support user applications.

/var

The /var directory contains files that change as the system is running.

/etc/hosts

This file lists the network host names and IP addresses that are intrinsically known to the system.

/boot

This is where the Linux kernel and boot loader files are kept. The kernel is a file called vmlinuz. Also in the /boot folder is ignited.img, which is a temporary file system used prior to loading the kernel and system.map, a symbol lookup table.

/etc/passwd

Traditionally, the /etc/passwd file is used to keep track of every registered user that has access to a system. It contains the following information: user name, encrypted password, user ID number (UID), user's group ID number (GID), Full name of the user (GECOS), User home directory, Login shell.

/usr/src

Source code files. If you installed the kernel source code package, you will find the entire Linux kernel source code here.

/media, /mnt

/media is a normal directory which is used in a special way. The /media directory is used for mount points. The process of attaching a device to the file system tree is called mounting. For a device to be available, it must first be mounted. When your system boots, it reads a list of mounting instructions in the file /etc/fstab, which describes which device is mounted at which mount point in the directory tree. This takes care of the hard drives, but you may also have devices that are considered temporary, such as CD-ROMs and floppy disks. Since these are removable, they do not stay mounted all the time. The /media directory is used by the automatic device mounting mechanisms found in modern desktop oriented Linux distributions. On systems that require manual mounting of removable devices, the /mnt directory provides a convenient place for mounting these temporary devices.

/tmp

/tmp is a directory in which programs can write their temporary files.

/usr/local

/usr/local and its subdirectories are used for the installation of software and other files for use on the local machine. What this really means is that software that is not part of the official distribution (which usually goes in /usr/bin) goes here. When you find interesting programs to install on your system, they should be installed in one of the /usr/local directories. Most often, the directory of choice is /usr/local/bin.

/usr/share/dict

Dictionaries for the spelling checker. See look and ispell

/var/log

Directory that contains log files. These are updated as the system runs. You should view the files in this directory from time to time, to monitor the health of your system.

/var/spool

The directory is used to hold files that are queued for some process, such as mail messages and print jobs. When a user's mail first arrives on the local system, the messages are first stored in /var/spool/mail

/etc/fastab

The fstab file contains a table of devices that get mounted when your system boots. This file defines your disk drives.

/usr/share/man

The man pages are kept here.

Root Directory (/)

The root directory is the first or top-most directory in a hierarchy. The first tier of directories within the root directory are fairly standardized on Unix-like operating systems. Directories typically installed by default include /bin, /boot, /dev, /etc, /home, /initrd, /lib, /lost+found, /misc, /mnt, /opt, /proc, /root, /sbin, /tmp, /usr and /var.

/sbin, /usr/sbin

The sbin directories contain programs for system administration, mostly for use by the superuser

/lib

The shared libraries are kept here.

/bin, /usr/bin

These two directories contain most of the programs for the system. The /bin directory has the essential programs that the system requires to operate, while /usr/bin contains applications for the system's users.

/etc/init.d

This directory contains the scripts that start various system services typically at boot time.

/usr/share/doc

Various documentation files in a variety of formats