2 - Raspberry PI Community Projects

8.9.5. List of Mount Points
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Mounting and unmounting
In a Unix-like system such as Debian, files are organized in a single tree-like
hierarchy of directories. The / directory is called the “root directory”; all additional
directories are sub-directories within this root. “Mounting” is the action
of including the content of a peripheral device (oen a hard drive) into the system's
general file tree. As a consequence, if you use a separate hard drive to
store users' personal data, this disk will have to be “mounted” in the /home/
directory. The root filesystem is always mounted at boot by the kernel; other
devices are oen mounted later during the startup sequence or manually with
the mount command.
Some removable devices are automatically mounted when connected, especially
when using the GNOME, KDE or other graphical desktop environments.
Others have to be mounted manually by the user. Likewise, they must be unmounted
(removed from the file tree). Normal users do not usually have permission
to execute the mount and umount commands. The administrator can,
however, authorize these operations (independently for each mount point) by
including the user option in the /etc/fstab file.
The mount command can be used without arguments (it then lists all mounted
filesystems). The following parameters are required to mount or unmount a
device. For the complete list, please refer to the corresponding man pages,
mount(8) and umount(8). For simple cases, the syntax is simple too: for example,
to mount the /dev/sdc1 partition, which has an ext3 filesystem, into
the /mnt/tmp/ directory, you would simply run mount -t ext3 /dev/sdc1 /
mnt/tmp/.
The /etc/fstab file gives a list of all possible mounts that happen either automatically on boot
or manually for removable storage devices. Each mount point is described by a line with several
space-separated fields:
• device to mount: this can be a local partition (hard drive, CD-ROM) or a remote filesystem
(such as NFS).
This field is frequently replaced with the unique ID of the filesystem (which you can determine
with blkid device) prefixed with UUID=. This guards against a change in the
name of the device in the event of addition or removal of disks, or if disks are detected in
a different order.
• mount point: this is the location on the local filesystem where the device, remote system,
or partition will be mounted.
• type: this field defines the filesystem used on the mounted device. ext3, vfat, ntfs, reise
rfs, xfs are a few examples.
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NFS, a network filesystem
NFS is a network filesystem; under Linux, it allows transparent access
to remote files by including them in the local filesystem.
Chapter 8 — Basic Configuration: Network, Accounts, Printing…
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