PART(8)

NAME
part - partition table editor

SYNOPSIS
part [device] ...

DESCRIPTION
Part is a screen oriented partition table editor.

On the screen you will see six lines of numbers, the first shows the device name and its geometry (number of cylinders, heads and sectors), the second shows the start and end of the drive or partition you are working on, the third to sixth line show the different partitions or subpartitions. All numbers but those on the second line can be edited.

Editing is a simple matter of moving around with the arrow keys and changing the values with + and - (or PgUp and PgDn), or by simply typing the desired value. The '?' key will give a small list of commands.

The spacebar toggles between showing the size of the partition and the last sector on the partition. It also modifies the way changes are interpreted. While "Size" is shown, part will not change the size of the partition, while "Last" is shown, you can modify begin and end of the partition separately.

The 'm' key is "magical", it lets you cycle through a set of interesting values for the base or size of a partition. These values are: Aligned to a cylinder, taped to other partitions (inside or outside), or filling out holes. Use this key !

Minix subpartition tables or extended partitions may be edited after hitting the '>' key. The number of this partition will be shown after the device name on the second row, e.g. /dev/hd0:2. Minix subpartition tables are shown as is, but extended partition bases are translated to absolute offsets on the screen to hide the gory details of their implementation from the innocent user. The '<' will bring you back to the enclosing partition table.

With arguments, part will use the given devices or files. Without arguments, part will use all interesting block devices in /dev sorted by device number and starting with /dev/hd0.

Values that are out of range, overlapping, or otherwise strange are shown in reverse video. Values that may possibly be a problem for operating systems other then Minix are shown in bold characters.

The name of the device is highlighted when it has not been read yet.

Head or sector numbers are highlighted if the partition does not start or end at a cylinder boundary.

The base and/or size field is highlighted if they fall outside the device, if they are inside some other partition, if the base equals the device's base (no room for the boot sector), or if the size is zero.

Part complies with the good old UNIX tradition of trusting the user. It will write any table, no matter how bad. You have been warned.

By the way, as far as Minix is concerned there is absolutely no reason to make partitions start precisely on a cylinder or track nor does it have to be exactly n cylinders long. Minix only looks at the base and size of a partition, the geometry of the drive doesn't have to be correct. Other Operating systems can be very picky about partitions that are not aligned. Some partition editors may refuse to edit a table, others may even make a mess of the table. The only exception is the first partition, it traditionally starts on the first track, not the first cylinder. All editors must understand this.

  Extended Partitions
Extended partitions are a mess that is only made slightly better by part by translating the base offsets to absolute numbers. It is better to use DOS fdisk to create them, but if you insist on using part then this is what they should look like:

    The extended partition entry in the primary partition table must cover the whole logical partition space within it.

    The area thus created is split in segments, each segment contains a partition table in sector 0 and one (just one) logical partition.

    The first entry of a segment's partition table describes this logical partition: it's partition ID, base and size.

    The second entry is an extended partition that describes base and size of the next segment (partition table and logical partition). The last segment's partition table is empty, or contains one logical partition.

SEE ALSO
fd(4), hd(4).

BUGS
You can have a table read, messed up, and written in no time, be careful.

You can't type head and sector numbers directly.

Sectors are counted from 0 for consistency, but the partition table counts from 1 like DOS addresses them. Most confusing.

You can't write a backup copy to a file, that's what dd(1) with count=1 is for.

AUTHOR
Kees J. Bot (kjb@cs.vu.nl)