Linux directories explanation

Root Filesystem

The contents of the root filesystem must be adequate to boot, restore, recover, and/or repair the system.

The following directories, or symbolic links to directories, are required in /.

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Directory                                  Description

bin                                            Essential command binaries
boot                                          Static files of the boot loader
dev                                            device files
etc                                             Host-specific system configuration
lib                                              Essential shared libraries and kernel modules
media                                       Mount point for removeable media
mnt                                           Mount point for mounting a filesystem temporarily
opt                                            Add-on application software packages
sbin                                           Essential system binaries
srv                                             Data for services provided by this system
tmp                                           Temporary files
usr                                             Secondary hierarchy
var                                             Variable data
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/bin : the bin directory contains several useful commands that are of use to both the system administrator as well as non-privileged user

/boot : for GRUB (GNU Grand Unified Bootloader). This directory contains everything required for the boot process.

/dev : the location of device files. In linux you have to remember that everything is a file or directory

/etc : contains all system related configuration files

/home : user home directories

/initrd : provides the capability to load a RAM disk by the bootloader this RAM disk can then be mounted as the root filesystem and programs can be run from it

/lib : contain kernel modules and those shared library

/lost+found : files that are recovered from crash or unproper shutdown are placed here

/media : this directory contains subdirectory which are used as mount points for removable media such as cdrom and flashdisk

/opt : reserve for all the software add-on packages that are not part of the default installation

/proc : this directory is special because it is also a virtual filesystem, it doesn’t contain real file but runtime system information (system memory, devices mounted, hardware configuration etc). It is also regarded as a control and information center for the kernel

/root : the home directory of the system administrator

/sbin : contain binaries essential for booting, restoring, recovering and/or repairing the system in addition to the binaries in /bin

/usr : contains all the user binaries their documentation, libraries, header files etc. This directory only contain read-only data

/var : contains variable data like system logging files

/srv : contains site-specific data which is served by the system

/tmp : this directory contains mostly files that are required temporarily.