Read Raw Sectors from a Disk Usage: dskread [-bcdEhHLS-] [-n name] [-N sectors] [-s size] [-t tracks] [ disk: ] [ <sectorlist> ] dskread copies low-level raw sectors on the disk you specify to stdout. In conjunction with dskwrite, dskread is most useful as a quick diskette duplication utility: you can read a whole diskette image into a file with dskread, then write it back out with dskwrite to a new diskette. But it's also useful for restoring a long stream of data dumped across a series of diskettes with dskwrite. The disk is given as a a single alphabetic drive letter plus a colon. If no disk is specified, the first logical drive is assumed (in most machines, this is the a: drive). Operation: dskread normally starts at cylinder 0, head 0, sector 0 and walks through the whole disk, reading all the sectors on a track under one head and then all tracks in a cylinder before repositioning the heads to the next cylinder. dskread always reads whole sectors except when reading from a file using the -d option. Options: -b Boot record. Skip sector 0 on the assumption it simply contains a standard boot record and parameter block corresponding to the particular media. -c Continuation. Assume the data has been split across several diskettes. After each disk has been read, prompt for the next one. If -d is specified also, the filename extension on each disk will be the disk number, i.e., 001, 002, 003, etc. -d Dummy filesystem. Assume the data is in a single file on the disk. If neither the -d nor the -b options is given, the disk will be read beginning with sector 0. -h Help. (This screen.) -n <name> The filename to look for if the -d (dummy file- system) option is used. Default is 'bindata'. -S Share the drive for read/write access by other processes. -- End of options. Formatting: Default is to let Windows NT try to determine the formatting that was used. If the disk was written in an unusual format or has non-standard data in sector 0, the following options can be used to override OS/2's attempt to guess the format: -E Extended density (2.88M) format. -H High density format. -L Low density format. -N <sectors> Sectors per track. -s <size> Sector size. Normally only 512 is supported but, depending on your hardware, you may also be able to create 128, 256 or 1024-byte sectors. -t <tracks> Number of tracks. Sector lists: Optionally, you can specify a list of sectors you want read. Sectors are given in (cylinder, head, sector) coordinates with parentheses around and commas or white space to separate the numeric values you write. Cylinders, heads and sectors are counted from zero and can be specified in decimal, hex or octal. A single sector specified alone means just that sector. Listing several separated by commas or spaces means each one individually. A pair of sectors joined by a hyphen means a range: all the consecutive sectors beginning with the first and running through to the second. Specifying a negative number as an ordinate means use the highest possible value for that disk. If any of the ordinates of a sector are omitted, they're assumed to be zero except when it closes a range, in which case it means use the highest possible value. Examples: 1. To duplicate a whole diskette image, autoformatting the output media if it's not already formatted: dskread a: > dskimage.a dskwrite -av a: < dskimage.a 2. To use a diskette as a serial archive media: The -d option allows you to request just enough dummy file system "envelope" around the otherwise arbitrary data you intend to write to ensure the disk can still be used with other Windows NT utilities. Here's an example writing the result of a tar'ing (archiving) a whole directory to a series of diskettes, again autoformatting: tar -cs mydir | dskwrite -avcd -n mydir a: It's restored with dskread -dc -n mydir a: | tar -xs The diskettes used do not all have to be the same density; any mix of high and low is okay. But remember that if a disk isn't already formatted, there's no way for dskwrite to tell whether it should be high or low density; any disks it has to format will all be formatted the same way. 3. Reading or writing tar-format floppies: Many UNIX machines support the use of a floppy as a tar archive media, just as if it were a tape. Every sector contains data; there's no filesystem and no boot record at all. This allows the greatest possible amount of data to be written to the disk and it does allow interchange with a UNIX machine, but tar-format floppies are not readable by any ordinary utilities. Here's an example, tar'ing mydir to a single tar-format floppy: tar -cs mydir | dskwrite -vx a: It's restored with dskread a: | tar -xs If the amount of data you're archiving is more than will fit on one diskette, use the -c option with dskread and dskwrite. But since there's no labeling recorded on the diskettes and the data just runs continuously from one diskette to the next, you will need to pay attention to the order in which they're written or read. |