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    Length: 3076 (0xc04)
    Types: TextFile
    Notes: UNIX file
    Names: »mkpt.8«

└─⟦26887b7e0⟧ Bits:30009717 Comet 32 harddisk image
    └─⟦28c352965⟧ »/a« UNIX Filesystem
        └─⟦this⟧ »usr/man/man8/mkpt.8« 

TextFile

.ig
	@(#)mkpt.8	Date: Late Twentieth Century
	@(#)Copyright (C) 1985 by Enea Data Svenska AB
..
.TH MKPT 8
.SH NAME
mkpt \- examine and modify disk partitions
.SH SYNOPSIS
.B /etc/mkpt
.SH DESCRIPTION
.I Mkpt
is an expanded version of a standard unix utility
for Comet32 genix.
It runs under an existing unix system,
and is used to interactively examine and modify 
disk partitions.
Its main use is for re\-configuring the system by
rewriting the disk header.
.LP
A
.I "partition table"
specifies the sizes and offsets of disk partitions
in terms of sectors (512 byte blocks).
There are two such tables: one in disk header and one in
disk driver in the kernel.
Normally when genix is booted the header table is copied
to the drive table.
Thus, if the header is modified, the change takes place
when genix is booted next time.
.LP
If the size or offset of a partition containing a file
system are modified, the file system is lost.
To re\-configure such file systems, you have to save
the contents on tape or floppy diskettes using
.IR tar (1)
or
.IR far (1),
and read back the contents after making an empty file
system in the modified partition.
.LP
Some things to be careful with:
The partitions
.IR dc0c
and
.IR dc1c
should always map the whole disk, including the header
(in fact,
.I mkpt
refuses to write the header if this is not the case).
The real genix root is in
.I dc1a
and the real swap area in
.I dc1b.
It is however possible to run unixes with both of
these on a floppy diskette (see
.IR vmflop (8)).
To change the size of the swap area (10000 sectors 
by default) one must also recompile the genix kernel 
with the new value of
.I NSWAP
(see
.IR vmunix (8)).
.LP
To write the header you must be logged in as root.
The values written are automatically recorded at the
end of /etc/partab.
.SH COMMANDS
On\-line help is included so everything need not be 
described here.
For most commands and keywords a unique abbreviation
is sufficient.
The best way to create a partition table is to make a file
containing lines such as
.nf

a      34000   100      ; root partition

.fi
The above line specifies an 'a' partition of 34000 sectors
beginning at sector 100 (right after disk header).
Suppose such a file is made and is named 
(for example) Partab40.
Then the following sequence of
.I mkpt
commands writes the table to the disk header:
.nf

> disk 1                ; select disk 1 (system disk)
> load Partab40         ; load file into workspace
> show work             ; make sure you got it
> write                 ; write workspace to header

.fi
.I Mkpt
tries to check that the table makes sense.
If you manage to write a bad table and cannot reboot the system,
use the floppy unix to re\-write the table.
.SH DIAGNOSTICS
The file
.I /vmsymbols
must be up\-to\-date.
.br
Lack of permissions to do various things.
.br
Inconsistencies noted in the system.
.br
Attempts to write bad data in the header.
.SH FILES
.nf
/usr/include/sys/disk.h         comet32 disk header
/etc/partab                     log file
.fi
.SH SEE ALSO
wd(4), disk(5), build(8), sysgen(8)