After installing the base system and writing to the Master Boot Record, you will be able boot Linux, but probably nothing else. This depends what you have chosen during the installation. This chapter will describe how you can reactivate your old systems so that you can also boot your DOS or Windows again.

LILO is a boot manager with which you can also boot other operating systems than Linux, which complies to PC conventions. The boot manager is configured via /etc/lilo.conf file. Whenever you edited this file you have to run lilo afterwards. The reason for this is that the changes will take place only when you call the program.

Important parts of the lilo.conf file are the lines containing the image and other keywords, as well as the lines following those. They can be used to describe a system which can be booted by LILO. Such a system can include a kernel (image), a root partition, additional kernel parameters, etc. as well as a configuration to boot another, non-Linux (other) operating system. These keywords can also be used more than once. The ordering of these systems within the configuration file is important because it determines which system will be booted automatically after, for instance, a timeout (delay) presuming LILO wasn't stopped by pressing the shift key.

After a fresh install of Debian, just the current system is configured for booting with LILO. If you want to boot another Linux kernel, you have to edit the configuration file /etc/lilo.conf to add the following lines:

image=/boot/vmlinuz.new
  label=new
  append="mcd=0x320,11"
  read-only

For a basic setup just the first two lines are necessary. If you want to know more about the other two options please have a look at the LILO documentation. This can be found in /usr/share/doc/lilo/. The file which should be read is Manual.txt. To have a quicker start into the world of booting a system you can also look at the LILO man pages lilo.conf for an overview of configuration keywords and lilo for description of the installation of the new configuration into the boot sector.

Notice that there are other boot loaders available in Debian GNU/Linux, such as GRUB (in grub package), CHOS (in chos package), Extended-IPL (in extipl package), loadlin (in loadlin package) etc.