/dev/
directory, for this purpose. Historically, /dev/hda
was the master disk on the first IDE controller, and /dev/hdb
its first slave, /dev/hdc
and /dev/hdd
being, respectively, the master and slave disks on the second IDE controller, and so on down for any others. /dev/sda
corresponded to the first SCSI drive, /dev/sdb
being the second, etc. This naming scheme has been unified with the Linux kernel present in Squeeze, and all hard drives (IDE/PATA, SATA, SCSI, USB, IEEE 1394) are now represented by /dev/sd*
.
/dev/sda1
is the first partition on the first disk, and /dev/sdb3
is the third partition on the second disk.
/dev/sda5
, followed by /dev/sda6
, etc.
udev
creates, in addition to /dev/sd*
, symbolic links with a fixed name, which you could then use if you wished to identify a hard drive in a non-ambiguous manner. These symbolic links are stored in /dev/disk/by-id
. On a machine with two physical disks, for example, one could find the following:
mirexpress:/dev/disk/by-id#ls -l
total 0 lrwxrwxrwx 1 root root 9 23 jul. 08:58 ata-STM3500418AS_9VM3L3KP -> ../../sda lrwxrwxrwx 1 root root 10 23 jul. 08:58 ata-STM3500418AS_9VM3L3KP-part1 -> ../../sda1 lrwxrwxrwx 1 root root 10 23 jul. 08:58 ata-STM3500418AS_9VM3L3KP-part2 -> ../../sda2 [...] lrwxrwxrwx 1 root root 9 23 jul. 08:58 ata-WDC_WD5001AALS-00L3B2_WD-WCAT00241697 -> ../../sdb lrwxrwxrwx 1 root root 10 23 jul. 08:58 ata-WDC_WD5001AALS-00L3B2_WD-WCAT00241697-part1 -> ../../sdb1 lrwxrwxrwx 1 root root 10 23 jul. 08:58 ata-WDC_WD5001AALS-00L3B2_WD-WCAT00241697-part2 -> ../../sdb2 [...] lrwxrwxrwx 1 root root 9 23 jul. 08:58 scsi-SATA_STM3500418AS_9VM3L3KP -> ../../sda lrwxrwxrwx 1 root root 10 23 jul. 08:58 scsi-SATA_STM3500418AS_9VM3L3KP-part1 -> ../../sda1 lrwxrwxrwx 1 root root 10 23 jul. 08:58 scsi-SATA_STM3500418AS_9VM3L3KP-part2 -> ../../sda2 [...] lrwxrwxrwx 1 root root 9 23 jul. 08:58 scsi-SATA_WDC_WD5001AALS-_WD-WCAT00241697 -> ../../sdb lrwxrwxrwx 1 root root 10 23 jul. 08:58 scsi-SATA_WDC_WD5001AALS-_WD-WCAT00241697-part1 -> ../../sdb1 lrwxrwxrwx 1 root root 10 23 jul. 08:58 scsi-SATA_WDC_WD5001AALS-_WD-WCAT00241697-part2 -> ../../sdb2 [...] lrwxrwxrwx 1 root root 9 23 jul. 16:48 usb-LaCie_iamaKey_3ed00e26ccc11a-0:0 -> ../../sdc lrwxrwxrwx 1 root root 10 23 jul. 16:48 usb-LaCie_iamaKey_3ed00e26ccc11a-0:0-part1 -> ../../sdc1 lrwxrwxrwx 1 root root 10 23 jul. 16:48 usb-LaCie_iamaKey_3ed00e26ccc11a-0:0-part2 -> ../../sdc2 [...] lrwxrwxrwx 1 root root 9 23 jul. 08:58 wwn-0x5000c50015c4842f -> ../../sda lrwxrwxrwx 1 root root 10 23 jul. 08:58 wwn-0x5000c50015c4842f-part1 -> ../../sda1 [...] mirexpress:/dev/disk/by-id#
lilo
. Forgetting to do so will render a system unable to boot if the old kernel was removed or replaced as the new one will not be in the same location on the disk.
/etc/lilo.conf
; a simple file for standard configuration is illustrated in the example below.
Example 8.3. LILO configuration file
# The disk on which LILO should be installed. # By indicating the disk and not a partition. # you order LILO to be installed on the MBR. boot=/dev/sda # the partition that contains Debian root=/dev/sda2 # the item to be loaded by default default=Linux # the most recent kernel image image=/vmlinuz label=Linux initrd=/initrd.img read-only # Old kernel (if the newly installed kernel doesn't boot) image=/vmlinuz.old label=LinuxOLD initrd=/initrd.img.old read-only optional # only for Linux/Windows dual boot other=/dev/sda1 label=Windows
grub-install /dev/sda
.
/boot/grub/grub.cfg
, but this file (in Debian) is generated from others. Be careful not to modify it by hand, since such local modifications will be lost the next time update-grub
is run (which may occur upon update of various packages). The most common modifications of the /boot/grub/grub.cfg
file (to add command line parameters to the kernel or change the duration that the menu is displayed, for example) are made through the variables in /etc/default/grub
. To add entries to the menu, you can either create a /boot/grub/custom.cfg
file or modify the /etc/grub.d/50_custom
file. For more complex configurations, you can modify other files in /etc/grub.d
, or add to them; these scripts should return configuration snippets, possibly by making use of external programs. These scripts are the ones that will update the list of kernels to boot: 10_linux
takes into consideration the installed Linux kernels; 20_linux
takes into account Xen virtual systems, and 30_os-prober
lists other operating systems (Windows, Mac OSX, Hurd).
grub-install /dev/sda
command.
/boot/grub/menu.lst
file (see example).
Example 8.4. GRUB configuration file
# Boot automatically after 30 seconds timeout 30 # Boot first entry by default default 0 # If that fails, try the second fallback 1 # Last kernel installed title GNU/Linux root (hd0,1) kernel /vmlinuz root=/dev/sda2 initrd /initrd.img # Old kernel (if the most recent doesn't boot) title GNU/Linux OLD root (hd0,1) kernel /vmlinuz.old root=/dev/sda2 initrd /initrd.img.old # Only for dual boot, Linux/Windows title Microsoft Windows rootnoverify (hd0,0) makeactive chainloader +1
ybin
program installs yaboot
and its configuration file. You will only need to run this command again if the /etc/yaboot.conf
is modified (it is duplicated on the bootstrap partition, and yaboot
knows how to find the position of the kernels on the disks).
ybin
, you must first have a valid /etc/yaboot.conf
. The following is an example of a minimal configuration.
Example 8.5. Yaboot configuration file
# bootstrap partition boot=/dev/sda2 # the disk device=hd: # the Linux partition partition=3 root=/dev/sda3 # boot after 3 seconds of inactivity # (timeout is in tenths of seconds) timeout=30 install=/usr/lib/yaboot/yaboot magicboot=/usr/lib/yaboot/ofboot enablecdboot # last kernel installed image=/vmlinux label=linux initrd=/initrd.img read-only # old kernel image=/vmlinux.old label=old initrd=/initrd.img.old read-only # only for Linux/Mac OSX dual-boot macosx=/dev/sda5 # bsd=/dev/sdaX and macos=/dev/sdaX # are also possible