--- name: "dskutil" section: "1" platform: "linux" package: "libdsk-utils" version: "1.5.9+dfsg-1+b2" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/dskutil" --- # dskutil(1) Simple sector edtor for discs and disc images. ## 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)](/sleep/3.md) function, the Z command works by busy-waiting. Commands are always input using [fgets(3)](/fgets/3.md), even when the host system provides a more sophisticated input method such as [readline(3)](/readline/3.md). 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 \.