In Linux various special files can be found under the directory
/dev. These files are called device files and
behave unlike ordinary files. The most common types of device files
are for block devices and character devices. These files are an
interface to the actual driver (part of the Linux kernel) which in
turn accesses the hardware. Another, less common, type of device file
is the named pipe.
The most important device files are listed in the tables below.
fd0 |
First Floppy Drive |
fd1 |
Second Floppy Drive |
hda |
IDE Hard disk / CD-ROM on the first IDE port (Master) |
hdb |
IDE Hard disk / CD-ROM on the first IDE port (Slave) |
hdc |
IDE Hard disk / CD-ROM on the second IDE port (Master) |
hdd |
IDE Hard disk / CD-ROM on the second IDE port (Slave) |
hda1 |
First partition of the first IDE hard disk |
hdd15 |
Fifteenth partition of the fourth IDE hard disk |
sda |
SCSI Hard disk with lowest SCSI ID (e.g. 0) |
sdb |
SCSI Hard disk with next higher SCSI ID (e.g. 1) |
sdc |
SCSI Hard disk with next higher SCSI ID (e.g. 2) |
sda1 |
First partition of the first SCSI hard disk |
sdd10 |
Tenth partition of the fourth SCSI hard disk |
sr0 |
SCSI CD-ROM with the lowest SCSI ID |
sr1 |
SCSI CD-ROM with the next higher SCSI ID |
ttyS0 |
Serial port 0, COM1 under MS-DOS |
ttyS1 |
Serial port 1, COM2 under MS-DOS |
psaux |
PS/2 mouse device |
gpmdata |
Pseudo device, repeater data from GPM (mouse) daemon |
cdrom |
Symbolic link to the CD-ROM drive |
mouse |
Symbolic link to the mouse device file |
null |
Anything written to this device will disappear |
zero |
One can endlessly read zeros out of this device |
The mouse can be used in both the Linux console (with gpm) and the X window environment. The two uses can be made compatible if the gpm repeater is used to allow the signal to flow to the X server as shown:
mouse => /dev/psaux => gpm => /dev/gpmdata -> /dev/mouse => X
/dev/ttyS0 (repeater) (symlink)
/dev/ttyS1
Set the repeater protocol to be raw (in /etc/gpm.conf) while
setting X to the original mouse protocol in /etc/X11/XF86Config
or /etc/X11/XF86Config-4.
This approach to use gpm even in X has advantages when the mouse is unplugged inadvertently. Simply restarting gpm with
# /etc/init.d/gpm restart
will re-connect the mouse in software without restarting X.
If gpm is disabled or not installed for some reason, make sure to set X to
read directly from a mouse device such as /dev/psaux. For details, refer
to the 3-Button Mouse mini-Howto at
/usr/share/doc/HOWTO/en-txt/mini/3-Button-Mouse.gz,
man gpm,
/usr/share/doc/gpm/FAQ.gz, and
README.mouse.