407 lines
14 KiB
HTML
407 lines
14 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN//2.0">
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<HTML>
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<HEAD>
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<TITLE>pdisk for the Mac OS</TITLE>
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<X-SAS-WINDOW TOP=42 BOTTOM=477 LEFT=4 RIGHT=556>
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</HEAD>
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<BODY BGCOLOR="#FFFFFF">
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<H2>Overview</H2>
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<H3>What is pdisk?</H3>
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<P>A simple editor for Apple disk partition format. There are two
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main versions of pdisk: one for Linux and one for the Mac OS. This
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document describes the Mac OS version of pdisk. Much of this document
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is also relevant to the Linux version, but check the manual page
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(pdisk.8) also.</P>
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<H3>What is the Apple disk partition format?</H3>
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<P>Most operating systems have ways to divide disks into several
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pieces - so that an entire disk does not have to be devoted to one
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filesystem, or even to one operating system. This division of the
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disk is usually called partitioning. In some systems the partitioning
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information is built into the operating system code, but that tends to
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be restrictive. In the Mac OS the partitioning information is stored
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on the first few blocks of the disk.</P>
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<P>The Apple disk partition scheme was developed in 1986 by the A/UX
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team with input from the Mac OS and Apple II teams. There was an
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earlier partition scheme used in the first SCSI drives on the
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MacPlus, but that was replaced by the current scheme in the Macintosh
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II and subsequent machines and in subsequent operating system
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releases. The current scheme is supported by Mac OS, A/UX, ProDos,
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MkLinux, LinuxPPC, and MacOS X.</P>
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<H3>What are LinuxPPC and MkLinux?</H3>
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<P>Just in case you got pdisk other than as part of a LinuxPPC or
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MkLinux release:</P>
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<P>LinuxPPC is a port of the true Linux operating system that runs
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on most of the Power Macintosh systems from Apple Computer. It also
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runs on several non-Apple PowerPC machines.</P>
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<P>MkLinux is a portion of the Linux operating system, converted to run
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as a server process on top of the Mach microkernel. As with Linux,
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all of the operating system source code is available for
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<A HREF="http://www.mklinux.org">download</A>, including the
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Mach source. MkLinux runs on some of PowerPC based Macintosh
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machines.</P>
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<H3>Which Macintosh machines does pdisk run on?</H3>
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<P>The Mac OS binary should run on any PowerPC based Macintosh. It
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has been tested under System 7.6.1 and System 8, but should run on
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older versions of the Mac OS as well. A Mac OS 68000 binary is also
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distributed for those who may find it useful. </P>
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<H3>Why would I want to use pdisk on the Mac OS?</H3>
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<P>The main clients for the Mac OS version of pdisk are Linux
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users. pdisk was originally developed for Linux. The command syntax
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was originally identical to that for the 'fdisk' program. (fdisk is a
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Linux program which edits the DOS/Windows disk partition format.) The
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Mac OS version is a simple, crude port of the Linux version.</P>
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<P>The advantages of pdisk over the various Mac OS disk partitioning
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programs (such as SilverLining, the FWB toolkit, Apple HD SC Setup,
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DriveSetup, etc) are:</P>
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<UL>
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<LI>unlike the Apple partitioners, it does not restrict the set of
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drives it can operate on
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<LI>it allows partitions to be reordered (helpful, as Linux
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depends on the order)
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<LI>it creates Linux partitions by default
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<LI>it allows the size of the partition map to be changed
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<LI>it allows the name of a partition to be changed
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<LI>it allows you to edit the partition map of your boot disk
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</UL>
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<P>The disadvantages of pdisk are:</P>
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<UL>
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<LI>it doesn't automatically initialize HFS partitions
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<LI>it can't install disk drivers
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<LI>it allows you to edit the partition map of your boot disk
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</UL>
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<H3>Where can I get the source?</H3>
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<P>The main site for LinuxPPC is
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<<A HREF="http://www.linuxppc.org">http://www.linuxppc.org</A>>.
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The main site for MkLinux is
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<<A HREF="http://www.mklinux.org">http://www.mklinux.org</A>>.
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</P>
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<H2>Description of the program (as of version 0.8)</H2>
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<P>Though pdisk is a Macintosh program its interface is very
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un-Macintosh. pdisk is what is called a line-oriented program. In a
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line-oriented program you do things by typing on the keyboard and the
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program does not pay attention to the typing until the return key has
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been typed.</P>
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<P>When you start up pdisk it brings up a window with some text in
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it. The last line of this text should be something like " Top level
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command (? for help): ". This is the prompt. If you type "?" followed
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by a return character you should get a list like this:</P>
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<PRE>Notes:
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Disk have fake names of the form /dev/scsi<bus>.<id>
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For example, /dev/scsi0.1, /dev/scsi1.3, and so on.
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Linux style names are also allowed (i.e /dev/sda or /dev/hda).
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Due to some technical problems these names may not match
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the 'real' linux names.
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Commands are:
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h print help
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v print the version number and release date
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l list device's map
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L list all devices' maps
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e edit device's map
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E (edit map with specified block size)
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r toggle readonly flag
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f toggle show filesystem name flag
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q quit the program</PRE>
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<P>Some of these commands need what are called arguments - for
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example <B>l</B> (list) and <B>e</B> (edit) need a single argument,
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the name of the device to list or edit. Commands which take arguments
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prompt for each argument in turn. You can also type any number of the
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arguments separated by spaces and those prompts will be skipped.
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Commands are case insensitive (e.g. <B>h</B> and <B>H</B>) except
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when the upper case letter does a variant form of the operation.</P>
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<DL>
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<DT><B>h</B>
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<DD>Prints just the command help. The difference between <B>h</B>
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and <B>?</B> is the latter prints some helpful notes as well.
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<DT><B>v</B>
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<DD>Prints a version number and release date. Matches the
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version in the GetInfo window for the application.
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<DT><B>l</B>
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<DD>Prompts for the name of the device and then lists the
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partition map on that device.
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<DT><B>L</B>
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<DD>Lists all the devices.
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<DT><B>e</B>
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<DD>Prompts for the name of the device and then opens the partition
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map for editing.
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<DT><B>E</B>
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<DD>Same as <B>e</B>, except also prompts for block size.
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<DT><B>r</B>
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<DD>Toggles read-only setting. When read-only is on pdisk will not
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write a partition map.
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<DT><B>f</B>
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<DD>Toggles show filesystem name flag between 'show fileystem name' and
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'show partition name'. The default is to show the filesystem name. Showing
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the filesystem name is helpful when you have several equal sized Macintosh
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partitions on the disk.
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<DT><B>q</B>
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<DD>Quit pdisk.
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</DL>
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<H3>The form of the listing</H3>
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<P>This is a good point to show what the partition map listing looks
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like.</P>
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<PRE>Partition map (with 512 byte blocks) on '/dev/scsi0.2' (/dev/sda)
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#: type name length base ( size )
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1: Apple_partition_map Apple 63 @ 1
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2: Apple_Driver43*Macintosh 54 @ 64
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3: Apple_Driver43*Macintosh 74 @ 118
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4: Apple_Patches Patch Partition 512 @ 192
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5: Apple_HFS untitled 2117430 @ 704 ( 1.0G)
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6: Apple_Free Extra 10 @ 2118134
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Device block size=512, Number of Blocks=2118143
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DeviceType=0x0, DeviceId=0x0
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Drivers-
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1: @ 64 for 20, type=0x1
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2: @ 118 for 32, type=0xffff</PRE>
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<P>The first line indicates what device this is and what size blocks
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the partition map is using. Most partition maps will use 512-byte
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blocks, but partition maps can use 1024-byte (1K) or 2048-byte (2K)
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blocks instead. If we are able to deduce an Linux name different
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from the name then the Linux name is given in parentheses.</P>
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<P>Next is the partition list. Each partition (or piece) of the disk
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takes one line of the list. The data describing the partition is
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called the partition map entry. The entries are listed in order by
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index. For each entry, the following information is displayed:</P>
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<UL>
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<LI>index - where the partition entry is in the map. This does not
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correspond the relative order of the partition contents and can
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change when the partition map is edited.
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<LI>type - the sort of data expected to be in the partition. pdisk
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doesn't put data into the contents of any partition except the
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partition map partition. The type is a case-insensitive string.
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<LI>name - the name is for the user's information. If the name
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is in quotes then it is the Mac volume name rather than actual
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partition name.
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<LI>length - the number of partition blocks the partition takes.
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<LI>base - the first block of the partition, measured in partition
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blocks, starting from zero.
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<LI>size - this is the length in bytes. Only shown if the size is
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at least one megabyte.
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</UL>
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<P>Following the partition list is information from block zero of the
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device which describes the location of drivers.</P>
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<H3>Editing Partition Tables</H3>
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<P>The <B>e</B> command at the top level menu opens a partition map
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for editing. The prompt is then changed to "Command (? for help):".
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If you type "?" followed by a return character you should get a list
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like this:</P>
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<PRE>Notes:
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Base and length fields are blocks, which vary in size between media.
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The name of a partition is descriptive text.
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Commands are:
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h help
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p print the partition table
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P (print ordered by base address)
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i initialize partition map
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s change size of partition map
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c create new partition (standard Linux type)
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C (create with type also specified)
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n (re)name a partition
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d delete a partition
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r reorder partition entry in map
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w write the partition table
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q quit editing (don't save changes)</PRE>
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<P>Commands which take arguments prompt for each argument in turn.
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You can also type any number of the arguments separated by spaces and
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those prompts will be skipped. The only exception to typeahead are
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the confirmation prompts on the <B>i</B> and <B>w</B> commands.
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Commands can are case insensitive (e.g. <B>h</B> and <B>H</B>) except
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when the upper case letter does a variant form of the operation.</P>
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<P>Partitions are always specified by their number, which the index
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of the partition entry in the partition map. Many of the commands
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will change the index numbers of other partitions besides the
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affected partition. You are advised to print the table as frequently
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as necessary.</P>
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<P>Creating more than fifteen partitions is not advised. There is
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currently a bug in the some (all?) of the kernels which causes access
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to the whole disk fail if more than fifteen partitions are in the
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map.</P>
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<DL>
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<DT><B>h</B>
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<DD>Prints just the command help. The difference between <B>h</B>
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and <B>?</B> is the latter prints some helpful notes as well.
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<DT><B>p</B>
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<DD>Prints the partition table. The form is identical to the
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listing described above.
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<DT><B>P</B>
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<DD>Identical to <B>p</B>, except the entries are listed in the
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order of the partitions on the disk (i.e. by the increasing base
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value) rather than in index order.
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<DT><B>i</B>
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<DD>Initializes the partition map (rarely used). This command
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prompts for the size of the device. WARNING - if you write the map
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after initializing it you will delete all the drivers on the device.
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That makes the device invisible to the Mac OS. pdisk is not able
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to install drivers.
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<DT><B>s</B>
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<DD>Change the size of the partition map partition. The partition
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map's size must be less than or equal to the size of the partition
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it is contained in. This is mostly useful when you want to do
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tricky things like making a disk with multiple partitioning
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schemes on it.
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<DT><B>c</B>
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<DD>Create a new partition takes three arguments.<BR>
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The first argument is the base address (in partition blocks) of
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the partition. Besides a raw number, you can also specify a
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partition number followed by the letter 'p' to indicate that the
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first block of the new partition should be the same as the first
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block of that existing free space partition.<BR>
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The second argument is the length of the partition in partition
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blocks. This can be a raw number or can be a partition number
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followed by the letter 'p' to use the size of that partition or
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can be a number followed by 'k', 'm', or 'g' to indicate the size
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in kilobytes, megabytes, or gigabytes respectively. (These are
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powers of 1024, of course, not powers of 1000.)<BR>
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The last argument is the name of the partition. This can be a
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single word without quotes, or a string surrounded by single or
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double quotes.<BR>
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The type of the created partition is set to the correct type for
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Linux ("Apple_UNIX_SVR2").
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<DT><B>C</B>
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<DD>Identical to the <B>c</B> command, with the addition of a
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prompt for the partition type after the other arguments. The type
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can be a single word without quotes, or a string surrounded by
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single or double quotes.
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<DT><B>n</B>
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<DD>Rename a partition. Do not change the name of any partition
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whose type starts with "Apple_Driver". The MacOS looks at the
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names of those partitions. All other partitions should be okay
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to change.
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<DT><B>d</B>
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<DD>Delete a partition. When a partition is deleted it's type is
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changed to free ("Apple_Free") and then it is combined with any
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adjacent free space.
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<DT><B>r</B>
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<DD>Reorder takes the current index and the desired new index. If
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you give a new index which is greater than the last index the
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entry will be moved to the last index.
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<DT><B>w</B>
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<DD>Write does write the partition map out, but pdisk does not yet
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flush the appropriate caches and unmount volumes so the partition
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map is not reinterpreted. In order to use the new partition map
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you must reboot your machine. Sorry.
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<DT><B>q</B>
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<DD>Quit out of editing. Returns to the top level prompt. If you
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have modified the partition map you are NOT asked if you want to
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save the changes, instead the changes are quietly thrown away.
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</DL>
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<H3>Known problems</H3>
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<DL>
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<DD>This is an awful Mac OS application, it should be rewritten
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to look the way a Mac OS app should look.
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<DD>The code assumes a better understanding of the partitioning
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scheme than most people care to acquire.
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<DD>
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<DD>Even more help should be available during user input.
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</DL>
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<P>
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<HR>
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</P>
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<ADDRESS><A HREF="mailto:eryk@cfcl.com">eryk@cfcl.com</A>
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</ADDRESS>
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