This is a small package that may be depended on by any bootloader

installer package to detect other filesystems with operating systems on

them, and work out how to boot other linux installs.

os-prober

---------

All one has to do is Depend on os-prober, and then run the os-prober

command. This command takes no arguments: it will scan all disks available

on the system for other operating systems, and output a list of strings

such as:

 /dev/sda1:Windows NT/2000/XP:WinNT:chain

 ^-------^ ^----------------^ ^---^ ^---^

   part.    OS name for boot  short May change: type of boot loader

            loader's pretty   name  required. Usually there is only

            output                  a 'linux' style bootloader or

                                    a chain one for other partitions

                                    with their own boot sectors.

Tests are executable programs in the directory /usr/libexec/os-probes/. Each

test is called once per partition, with the partition to check as its

parameter, and may output a string as described above, or nothing if it does

not recognise an OS on that partition. Tests return an exit code of 0

if they successfully found an OS, and no further tests will be run on that

partition; or return an exit code of 1 to indicate that no OS was found,

and let the next test run.

Tests that require the partition to be mounted can be placed in

/usr/libexec/os-probes/mounted/. These tests are passed the following

parameters: partition, mount point, filesystem.

Bootloader installer packages will then have to process this output (fairly

trivial) to create valid configuration entries for the bootloader.

Note that os-prober can find other Linux installations, as well as other

operating systems. It does not try to work out all the information needed

to boot Linux (initrd, kernel params, etc). That task is left to

linux-boot-prober.

linux-boot-prober

-----------------

The linux-boot-prober command should be run with a single argument

consisting of a partition that is known to have a linux root filesystem on

it, as returned by the os-prober command. It will try to work out how to

boot that linux installation, and if it is successful, will output one or

more lines in the form:

 /dev/sda2:/dev/sda1:Linux:/vmlinuz:/initrd.gz:root=/dev/sda1

 ^-------^ ^-------^ ^---^ ^------^ ^--------^ ^------------^

   root      boot    label  kernel    initrd    kernel params

   part.     part.

The root partition and boot partition may of course be the same. No guarantee

is made that any partitions referred to in the kernel parameters will still be

in the same place after Debian is installed, or that the /etc/fstab of the

system will be right, or that the system will even boot. The initrd field may

be empty if there is no initrd. The label is whatever label was used in the

boot loader for this linux installation, and it may be quite long or very

short (or nonexistent), and may be inaccurate, confusing, or non-unique. See

TODO for other limitations.

The tests used by linux-boot-prober are in the directory

/usr/libexec/linux-boot-probes/ and also in /usr/libexec/linux-boot-probes/mounted,

and they are called in a similar way as the os-probes described above.

The mounted probes are passed parameters for the root partition, the boot

partition, and the directory the filesystems are mounted in.

linux-boot-prober skips over partitions that are currently mounted on /,

/target, or /target/boot.