instbb(ADM)

instbb -- install a hard disk or floppy disk boot block

Syntax

/etc/instbb [ -vqny ] [ -d dir ] [ -f type ] media file

Description

instbb installs a boot block suitable for the media peripheral in file. The dir argument to the -d option specifies where the boot blocks to install are located (default is /etc). The remaining options are used only if the media is a floppy disk.

The bootable media types are shown in the following table (all media except hd are assumed to be floppy disks):

hd: hard disk
96ds15: 5¼-inch, 96 sectors/track, 15 tracks/inch, double-sided floppy disk
135ds18: 3½-inch, 135 sectors/track, 18 tracks/inch, double-sided floppy disk
48ds9: 5¼-inch, 48 sectors/track, 9 tracks/inch, double-sided floppy disk
96ds18: 5¼-inch, 96 sectors/track, 18 tracks/inch, double-sided floppy disk
135ds9: 3½-inch, 135 sectors/track, 9 tracks/inch, double-sided floppy disk
96ds9: 5¼-inch, 96 sectors/track, 9 tracks/inch, double-sided floppy disk

On hd (hard disk) media, dir /hdboot0 is installed in the first 1KB and dir /hdboot1 is installed in the subsequent 20 Kbytes. file is normally an active virtual hard disk such as /dev/hd0a.

On the various floppy disk media, the 1 Kbyte boot block, dir /fdmediaboot0, is installed in one or two pieces depending on the type of filesystem floppy disk that file contains. If no -f type option is specified, instbb uses fstyp(ADM) to deduce the type of filesystem contained by file.

On XENIX and unknown filesystems, instbb places the boot block in the first two sectors.

On S51K, AFS, ES51K, and EAFS filesystems, instbb places the boot block in the first and third sectors.

The following options apply to floppy disk media only:

-v: Check any type specified with -f against what fstyp reports. For safety, this is the default behavior.
-q: Believe any type specified with -f rather than checking it against what fstyp reports. This is the inverse of -v, so at most one of -q and -v should be specified.
-n: Produce a fatal error if the specified type and the filesystem type reported by fstyp differ, or no type was specified and fstyp cannot deduce the type. file is not modified. For safety, this is the default behavior.
-y: Issue a warning if the specified type and the filesystem type reported by fstyp differ, or no type was specified and fstyp cannot deduce a type. A boot block is installed using any filesystem type specified using -f. This is the inverse of -y, so at most one of -n and -y should be specified.

If neither -y nor -n is specified, and type does not match what fstyp reports, then the user is prompted whether or not to proceed:

An answer of ``n'' is equivalent to -n; no boot block is installed and file is not modified. For safety, this is the default answer.

An answer of ``y'' is equivalent to -y; the boot block is installed using the filesystem type specified by -f.

Examples

The minimum set of commands to make the formatted 3½-inch 1.44MB floppy disk in drive 0 bootable is:

mkfs /dev/fd0135ds18 2880
mount /dev/fd0135ds18 /mnt
cp /boot /mnt/boot
umount /dev/fd0135ds18
instbb 135ds18 /dev/fd0135ds18

The floppy disk will be difficult to use as it does not contain an appropriate /etc/default/boot, or any other useful files, but is sufficient to get to the boot prompt.

Limitations

instbb does not make file bootable. The filesystem contained in file must also include boot in its root directory. Hard disks must be partitioned with fdisk(ADM) and divvy(ADM), and contain an appropriate masterboot block. See boot(HW) for details.

mkfs(ADM) should be run before instbb. mkdev(ADM) runs the proper commands in the correct order.

Files