Physical Layout - Raspberry Pi A User Manual

54

Physical Layout

Although the preceding list is how the file system appears to the Linux operating system, it's
not how it's laid out on the SD card itself. For the default Raspbian distribution, the SD card is
organised into two main sections, known as partitions because they split the device into differ-
ent areas in much the same way as the chapters of this book help to organise its contents.
The first partition on the disk is a small (approximately 75 MB) partition formatted as VFAT,
the same partition format used by Microsoft Windows for removable drives. This is mounted,
or made accessible, by Linux in the
configure the Raspberry Pi and to load Linux itself.
P A R T I
etc—This stores miscellaneous configuration files, including the list of users and their
❍
encrypted passwords.
home—Each user gets a subdirectory beneath this directory to store all their personal
❍
files.
lib—This is a storage space for libraries, which are shared bits of code required by
❍
numerous different applications.
lost+found—This is a special directory where file fragments are stored if the system
❍
crashes.
media—This is a special directory for removable storage devices, like USB memory
❍
sticks or external CD drives.
mnt—This folder is used to manually mount storage devices, such as external hard drives.
❍
opt—This stores optional software that is not part of the operating system itself. If
❍
you install new software to your Pi, it will usually go here.
proc—This is another virtual directory, containing information about running pro-
❍
grams, which are known in Linux as processes.
selinux—Files related to Security Enhanced Linux, a suite of security utilities originally
❍
developed by the US National Security Agency.
sbin—This stores special binary files, primarily used by the root (superuser) account
❍
for system maintenance.
sys—This directory is where special operating system files are stored.
❍
tmp—Temporary files are stored here automatically.
❍
usr—This directory provides storage for user-accessible programs.
❍
var—This is a virtual directory that programs use to store changing values or variables.
❍
C O N N E C T I N G T H E B O A R D
directory and contains all the files required to
/boot