161 lines
4.0 KiB
Groff
161 lines
4.0 KiB
Groff
.\" Copyright (c) 2024 DTB <trinity@trinity.moe>
|
|
.\"
|
|
.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
|
|
.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
|
|
|
|
.TH dj 1
|
|
|
|
.SH NAME
|
|
|
|
dj \(en disk jockey
|
|
|
|
.SH SYNOPSIS
|
|
|
|
dj
|
|
.RB ( -AdHnq )
|
|
.RB ( -a
|
|
.RB [ byte ])
|
|
.RB ( -c
|
|
.RB [ count ])
|
|
|
|
.RB ( -i
|
|
.R [
|
|
.B input file
|
|
.R ])
|
|
.RB ( -b
|
|
.R [
|
|
.B input block size
|
|
.R ])
|
|
.RB ( -s
|
|
.R [
|
|
.B input offset
|
|
.R ])
|
|
|
|
.RB ( -o
|
|
.R [
|
|
.B output file
|
|
.R ])
|
|
.RB ( -B
|
|
.R [
|
|
.B output block size
|
|
.R ])
|
|
.RB ( -S
|
|
.R [
|
|
.B output offset
|
|
.R ])
|
|
|
|
.SH USAGE
|
|
|
|
The
|
|
.B -i
|
|
option takes a path as an argument to open and use in place of standard input.
|
|
The
|
|
.B -o
|
|
option does the same in place of standard output. Dj does not truncate output
|
|
files and instead writes over the bytes in the existing file.
|
|
.PP
|
|
The
|
|
.B -b
|
|
option takes a numeric argument as the size in bytes of the input buffer and
|
|
the
|
|
.B -B
|
|
option does the same for the output buffer, the default for both being 1024
|
|
bytes, or one kibibyte (KiB).
|
|
.PP
|
|
The
|
|
.B -s
|
|
option takes a numeric argument as the number of bytes to skip into the input
|
|
before starting to read, and the
|
|
.B -S
|
|
option skips a number of bytes through the output before starting to write from
|
|
the input. If the input is a stream the bytes are read and discarded. If the
|
|
output is a stream, nul characters are printed.
|
|
.PP
|
|
The
|
|
.B -a
|
|
option takes one argument of one byte in length and pads the input buffer with
|
|
that byte in the event that a read doesn't fill the input buffer, and the
|
|
.B -A
|
|
option takes no arguments and pads with nuls.
|
|
The
|
|
.B -c
|
|
option specifies an amount of reads to make, and if 0 (the default) dj will
|
|
continue reading until a partial or empty read.
|
|
.PP
|
|
On a partial or empty read, dj prints a diagnostic message (unless the
|
|
.B -q
|
|
option is specified) and exits (unless the
|
|
.B -n
|
|
option is specified, in which case only two consecutive empty reads will cause
|
|
dj to exit).
|
|
At exit, usage statistics are printed unless the option
|
|
.B -q
|
|
is specified a second time. The
|
|
.B -H
|
|
option will make these diagnostics human-readable.
|
|
|
|
.SH DIAGNOSTICS
|
|
|
|
The
|
|
.B -d
|
|
option prints all information, user-specified or otherwise, before program
|
|
execution.
|
|
.PP
|
|
When dj exits, by default statistics are printed for input and output to
|
|
standard error in the following format:
|
|
.PP
|
|
.R {records read} {ASCII unit separator} {partial records read}
|
|
.R {ASCII record separator} {records written} {ASCII unit separator}
|
|
.R {partial records written} {ASCII group separator} {bytes read}
|
|
.R {ASCII record separator} {bytes written} {ASCII file separator}
|
|
.PP
|
|
If the
|
|
.B -H
|
|
option is specified dj instead uses this following format:
|
|
.PP
|
|
.R {records read} '+' {partial records read} '>' {records written}
|
|
.R '+' {partial records written} ';' {bytes read} '>' {bytes written}
|
|
.R {ASCII line feed}
|
|
.PP
|
|
The
|
|
.B -q
|
|
option suppresses error messages which print when a read or write is partial or
|
|
empty and when used twice suppresses diagnostic output entirely.
|
|
.PP
|
|
In non-recoverable errors that don't pertain to dj's read-write cycle, a
|
|
diagnostic message is printed and dj exits with the appropriate sysexits(3)
|
|
status.
|
|
|
|
.SH BUGS
|
|
|
|
If
|
|
.B -n
|
|
is specified along with a specified count, actual byte output may be lower than
|
|
expected (the product of the count multiplied by the input block size). If the
|
|
.B -a
|
|
or
|
|
.B -A
|
|
options are used this could make data written nonsensical.
|
|
.PP
|
|
Many lowercase options have capitalized variants and vice-versa which can be
|
|
confusing. Capitalized options tend to affect output or are more intense
|
|
versions of lowercase options.
|
|
|
|
.SH RATIONALE
|
|
|
|
Dj was modeled after the dd utility specified in POSIX but adds additional
|
|
features: typical option formatting, allowing seeks to be specified in bytes
|
|
rather than in blocks, allowing arbitrary bytes as padding, and printing in a
|
|
format that's easy to parse for machines. It also neglects character
|
|
conversion, which may be dd's original intent but is irrelevant to its modern
|
|
use.
|
|
|
|
.SH COPYRIGHT
|
|
|
|
Copyright (C) 2023 DTB. License AGPLv3+: GNU AGPL version 3 or later
|
|
<https://gnu.org/licenses/agpl.html>.
|
|
|
|
.SH SEE ALSO
|
|
|
|
dd(1)
|