The Debian Administrator's Handbook

An HTTP proxy is a server that forwards an HTTP request for network users. It sometimes helps to speed up downloads by keeping a copy of files that have been transferred through it (we then speak of proxy/cache). In some cases, it is the only means of accessing an external web server; in such cases it is essential to answer the corresponding question during installation for the program to be able to download the Debian packages through it.

Squid is the name of the server software used by Falcot Corp to offer this service.

4.2.16. Debian Package Popularity Contest

The Debian system contains a package called popularity-contest, whose purpose is to compile package usage statistics. Each week, this program collects information on the packages installed and those used recently, and anonymously sends this information to the Debian project servers. The project can then use this information to determine the relative importance of each package, which influences the priority that will be granted to them. In particular, the most “popular” packages will be included in the installation CD-ROM, which will facilitate their access for users who do not wish to download them or to purchase a complete set.

This package is only activated on demand, out of respect for the confidentiality of users' usage.

4.2.17. Selecting Packages for Installation

The following step allows you to choose the purpose of the machine in very broad terms; the ten suggested tasks correspond to lists of packages to be installed. The list of the packages that will actually be installed will be fine-tuned and completed later on, but this provides a good starting point in a simple manner.

Some packages are also automatically installed according to the hardware detected (thanks to the program discover-pkginstall from the discover package). For instance, if a VirtualBox virtual machine is detected, the program will install the virtualbox-ose-guest-dkms package, allowing for better integration of the virtual machine with the host system.

Figure 4.13. Task choices

4.2.18. Installing the GRUB Bootloader

The bootloader is the first program started by the BIOS. This program loads the Linux kernel into memory and then executes it. It often offers a menu that allows the user to choose the kernel to load and/or the operating system to boot.

BEWARE Bootloader and dual boot

This phase in the Debian installation process detects the operating systems that are already installed on the computer, and automatically adds corresponding entries in the boot menu, but not all installation programs do this.

In particular, if you install (or reinstall) Windows thereafter, the bootloader will be erased. Debian will still be on the hard drive, but will no longer be accessible from the boot menu. You would then have to boot the Debian installation system in rescue mode to set up a less exclusive bootloader. This operation is described in detail in the installation manual.

→ http://www.debian.org/releases/stable/i386/ch08s07.html

By default, the menu proposed by GRUB contains all the installed Linux kernels, as well as any other detected operating systems. This is why you should accept the offer to install it in the Master Boot Record. Since keeping older kernel versions preserves the ability to boot the same system if the most recently installed kernel is defective or poorly adapted to the hardware, it is best to always keep at least three older versions.

GRUB is the default bootloader installed by Debian thanks to its technical superiority: it works with most filesystems and therefore doesn't require an update after each installation of a new kernel, since it reads its configuration during boot and finds the exact position of the new kernel. Version 1 of GRUB (now known as “Grub Legacy”) couldn't handle all combinations of LVM and software RAID; version 2, installed by default, is more complete. There may still be situations where it is more recommendable to install LILO (another bootloader); the installer will suggest it automatically.

For more information on configuring GRUB, please refer to Section 8.8.3, “GRUB 2 Configuration”.

BEWARE Bootloaders and architectures

LILO and GRUB, which are mentioned in this chapter, are bootloaders for i386 and amd64 architectures. If you install Debian on another architecture, you will need to use another bootloader. Among others, we can cite yaboot or quik for powerpc, silo for sparc, elilo for ia64, aboot for alpha, arcboot for mips, atari-bootstrap or vme-lilo for m68k.

4.2.19. Finishing the Installation and Rebooting