In Linux you have various special files in /dev. These files are called device files. In the Unix world accessing hardware is different. There you have a special file which actually runs a driver which in turn accesses the hardware. The device file is an interface to the actual system component. Files under /dev also behave differently than ordinary files. Below are the most important device files listed.
| 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 | Everything pointed 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 with some reason, make sure to set X to read directly from the 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.