NAME

       dskutil - Simple sector edtor for discs and disc images.

SYNOPSIS

       dskutil [-type TYPE] [-side SIDE] [-comp COMP] [-dstep] [-retry COUNT] [-format FMT] DISKIMAGE

DESCRIPTION

       dskutil  is an interactive command-driven sector editor, patterned after the venerable CP/M sector editor
       DU90. This explains some of its idiosyncracies, such as the fact that  commands  deal  in  logical  track
       numbers but physical sector numbers.

OPTIONS

       -type TYPE
              Determines which LibDsk driver is to be used to access the disc.

              auto    Select according to the disc image file. This is the default.

              dsk     Use the DSK (CPCEmu format) image driver.

              edsk    Use the extended version of the DSK format.

              floppy  Use the floppy driver.

              myz80   Use the hard disk (MYZ80 format) image driver.  (This format cannot be autodetected.)

              cfi     Use the CFI (DOS fdcopy format) image driver.  (This format cannot be autodetected.)

              apridisk
                      Use the ApriDisk image driver (from the utility of the same name).  (This format cannot be
                      autodetected.)

              raw     Use the raw driver.

       -comp COMP
              Select the compression method used on the disc image file (has no effect  when  reading  a  floppy
              disc).

              auto    Detect from the first few bytes of the file. This is the default.

              sq      Huffman coded (SQ / USQ).

              gz      Gzipped (gzip / gunzip).

              bz2     Burrows-Wheeler compressed (bzip2 / bunzip2).

       -side SIDE
              Determines  which side (0 or 1) of the source disc is to be scanned. If this option is not present
              both sides will be scanned.

       -dstep Double-step the source drive (used to read 360k discs in 1.2Mb  drives).  Only  supported  by  the
              Linux floppy driver.

       -retry COUNT
              Set the number of times to attempt a read/write/format in case of error.

       -format FMT
              Do  not autodetect the disc format; use the named format. The format need only be an approximation
              to the actual format used by the disc.

       -first CYL
              Start scanning at the specified cylinder.

       -last CYL
              Scan up to and including the specified cylinder.

COMMANDS

       The following single-letter commands are used. Operands in brackets  such  as  [filename]  are  optional.
       Numeric inputs are shown as nn for decimal, and xx for hex. In either case, prefixing the number with "#"
       selects the alternate number system.

       Multiple commands on a line are allowed, separated by semicolons.

       +[x]   Increase the current sector number by [x] and read the resulting sector, incrementing the track if
              necessary.

       -[x]   Decrease the current sector number by [x] and read the resulting sector, decrementing the track if
              necessary.

       #      Display the disc geometry for the current drive/disc image.

       $[variable[=value]]
              View and amend the geometry. "$" by itself shows all possible variables with their current values;
              "$variable"  shows  the  value  of one variable; and "$variable=value" sets a new value. Note that
              changing the size of the sector with "$secsize=nn" will cause the current sector buffer  and  clip
              buffer to be cleared.

       =ascii Search for an ASCII string, starting at the current sector. Hex codes can be included in the ASCII
              by surrounding them with angle brackets - for example, to search for the word "Hello" at the start
              of a line, you could use "=<0A>Hello". The search string is case-sensitive.

       <      Save the currently-loaded sector to a clip buffer.

       >      Restore the contents of the clip buffer to the current sector buffer.

       ?      Display a command summary.

       A[from,to]
              Dump  the  contents  of  the sector buffer as ASCII. If from and to are included, then only values
              between those offsets will be shown.

       CHoffset,value,value,value...
              Change bytes in the current sector buffer. The offset and values are in hex.

       CAoffset,ascii
              Replace bytes in the current sector buffer with an ASCII string. As  with  the  "="  command,  the
              ASCII can contain embedded hex bytes in angle brackets.

       CHfrom-to,value,value,value...
              The  same  as  CH  above, but fills the range from from to to with the byte sequence, repeating or
              truncating it as necessary.

       CAfrom-to,ascii
              The same as CHfrom-to, except that the byte sequence is specified as ASCII.

       D[from,to]
              Dump the contents of the sector buffer as ASCII and hex.

       Gxx    Go to logical sector number xx

       H[from,to]
              Dump the contents of the sector buffer as hex.

       Kfilename
              Save all "yanked" sectors (see Y below) to the specified file. This also clears them from memory.

       Lfilename[,type[,compression]]
              Open a new drive or disc image. If this has a different sector size from the current sector  size,
              the sector buffer and clip buffer will be cleared.

       N[geometry]
              Change  geometry.  N  by itself re-runs the automatic probe; N with the name of a geometry selects
              one of the formats known to LibDsk.

       R      (Re)read the current sector.

       Snn    Set the current sector number, and read.

       Tnn    Set the current track number. Does not read.

       V      Compare the contents of the sector buffer with the current sector on disc.

       W      Write the sector buffer to disc.

       X      Leave dskutil.

       Y      Append the current sector to a "yank" buffer. It can then be saved with the K command.

       Z[nn]  Sleep for nn seconds; if nn is not present, sleeps for one second.

       /nn    This must be the last command on a line. It repeats the preceding line nn times.

BUGS

       On platforms with no sleep(3) function, the Z command works by busy-waiting.

       Commands are always input using fgets(3), even when the host system provides a more  sophisticated  input
       method such as readline(3).

       While  the  current  feature  set is a fairly good match for DU90 (less the features specific to the CP/M
       filesystem) it doesn't cover all the features of LibDsk.

AUTHOR

       John Elliott <seasip.webmaster@gmail.com>.