Appendix C. Random Bits

Appendix C. Random Bits

C.1. Linux Devices

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.

Device file	Description
fd0	First Floppy Drive
fd1	Second Floppy Drive
sda	First hard disk
sdb	Second hard disk
sda1	First partition of the first hard disk
sdb7	Seventh partition of the second hard disk
sr0	First CD-ROM
sr1	Second CD-ROM
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

C.1.1. Setting Up Your Mouse

The mouse can be used in both the Linux console (with gpm) and the X window environment. Normally, this is a simple matter of installing gpm and the X server itself. Both should be configured to use /dev/input/mice as the mouse device. The correct mouse protocol is named exps2 in gpm, and ExplorerPS/2 in X. The respective configuration files are /etc/gpm.conf and /etc/X11/xorg.conf.

Certain kernel modules must be loaded in order for your mouse to work. In most cases the correct modules are autodetected, but not always for old-style serial and bus mice[6], which are quite rare except on very old computers. Summary of Linux kernel modules needed for different mouse types:

Module	Description
psmouse	PS/2 mice (should be autodetected)
usbhid	USB mice (should be autodetected)
sermouse	Most serial mice
logibm	Bus mouse connected to Logitech adapter card
inport	Bus mouse connected to ATI or Microsoft InPort card

To load a mouse driver module, you can use the modconf command (from the package with the same name) and look in the category kernel/drivers/input/mouse.

C.2. Disk Space Needed for Tasks

A standard installation for the amd64 architecture, including all standard packages and using the default kernel, takes up 822MB of disk space. A minimal base installation, without the “Basic Ubuntu server” task selected, will take 506MB.

Important

In both cases, this is the actual disk space used after the installation is finished and any temporary files deleted. It also does not take into account overhead used by the file system, for example for journal files. This means that significantly more disk space is needed both during the installation and for normal system use.

The following table lists sizes reported by aptitude for the tasks listed in tasksel. Note that some tasks have overlapping constituents, so the total installed size for two tasks together may be less than the total obtained by adding up the numbers.

By default, the installer will install the LXQt desktop environment, but alternative desktop environments can be selected either by using one of the special CD images or by specifying the desired desktop environment when the installer is booted.

Note that you will need to add the sizes listed in the table to the size of the standard installation when determining the size of partitions. Most of the size listed as “Installed size” will end up in /usr and in /lib; the size listed as “Download size” is (temporarily) required in /var.

Task	Installed size (MB)	Download size (MB)	Space needed to install (MB)
Desktop environment
• GNOME	2487	765	3252
• KDE	2198	770	2968
• Xfce	1529	503	2032
• LXQt (default)	1536	502	2038
Web server	31	7	38
Print server	234	73	307

If you install in a language other than English, tasksel may automatically install a localization task, if one is available for your language. Space requirements differ per language; you should allow up to 350MB in total for download and installation.

C.3. Disk Space Needed

Minimal server installation of atomeOS bionic beaver requires 400MB of disk space. The standard atomeOS desktop installation requires 2GB.

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[6]

Serial mice usually have a 9-hole D-shaped connector; bus mice have an 8-pin round connector, not to be confused with the 6-pin round connector of a PS/2 mouse or the 4-pin round connector of an ADB mouse.