/*
* *****************************************************************************
*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2018-2025 Gavin D. Howard and contributors.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* *****************************************************************************
*
* The dc help text.
*
*/
usage: %s [options] [file...]
dc is a reverse-polish notation command-line calculator which supports unlimited
precision arithmetic. For details, use `man %s` or see the online documentation
at https://github.com/gavinhoward/bc/tree/%s/manuals/dc/%s.1.md .
This dc is (mostly) compatible with the OpenBSD dc and the GNU dc. See the
OpenBSD man page (http://man.openbsd.org/OpenBSD-current/man1/dc.1) and the GNU
dc manual (https://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html)
for details.
This dc has a few differences from the two above:
1) When printing a byte stream (command "P"), this bc follows what the FreeBSD
dc does.
2) This dc implements the GNU extensions for divmod ("~") and modular
exponentiation ("|").
3) This dc implements all FreeBSD extensions, except for "J" and "M".
4) This dc does not implement the run command ("!"), for security reasons.
5) Like the FreeBSD dc, this dc supports extended registers. However, they are
implemented differently. When it encounters whitespace where a register
should be, it skips the whitespace. If the character following is not
a lowercase letter, an error is issued. Otherwise, the register name is
parsed by the following regex:
[a-z][a-z0-9_]*
This generally means that register names will be surrounded by whitespace.
Examples:
l idx s temp L index S temp2 < do_thing
Also note that, unlike the FreeBSD dc, extended registers are not even
parsed unless the "-x" option is given. Instead, the space after a command
that requires a register name is taken as the register name.
Options:
-C --no-digit-clamp
Disables clamping of digits that are larger than or equal to the current
ibase when parsing numbers.
This means that the value added to a number from a digit is always that
digit's value multiplied by the value of ibase raised to the power of the
digit's position, which starts from 0 at the least significant digit.
If multiple of this option and the -c option are given, the last is used.
-c --digit-clamp
Enables clamping of digits that are larger than or equal to the current
ibase when parsing numbers.
This means that digits that the value added to a number from a digit that
is greater than or equal to the ibase is the value of ibase minus 1 all
multiplied by the value of ibase raised to the power of the digit's
position, which starts from 0 at the least significant digit.
If multiple of this option and the -C option are given, the last is used.
{{ A H N HN }}
-E seed --seed=seed
Sets the builtin variable seed to the given value assuming that the given
value is in base 10. It is a fatal error if the given value is not a valid
number.
{{ end }}
-e expr --expression=expr
Run "expr" and quit. If multiple expressions or files (see below) are
given, they are all run. After running, dc will exit.
-f file --file=file
Run the dc code in "file" and exit. See above.
-h --help
Print this usage message and exit.
-I ibase --ibase=ibase
Sets the builtin variable ibase to the given value assuming that the given
value is in base 10. It is a fatal error if the given value is not a valid
number.
-i --interactive
Put dc into interactive mode. See the man page for more details.
-L --no-line-length
Disable line length checking.
-O obase --obase=obase
Sets the builtin variable obase to the given value assuming that the given
value is in base 10. It is a fatal error if the given value is not a valid
number.
-P --no-prompt
Disable the prompts in interactive mode.
-R --no-read-prompt
Disable the read prompt in interactive mode.
-S scale --scale=scale
Sets the builtin variable scale to the given value assuming that the given
value is in base 10. It is a fatal error if the given value is not a valid
number.
-V --version
Print version and copyright and exit.
-x --extended-register
Enable extended register mode.
-z --leading-zeroes
Enable leading zeroes on numbers greater than -1 and less than 1.
Environment variables:
DC_ENV_ARGS
Command-line arguments to use on every run.
DC_LINE_LENGTH
If an integer, the number of characters to print on a line before
wrapping. Using 0 will disable line length checking.
DC_SIGINT_RESET
If an integer and non-zero, reset on SIGINT, rather than exit, when in
interactive mode.
If zero, do not reset on SIGINT in all cases, but exit instead.
Overrides the default, which is %s.
DC_TTY_MODE
If an integer and non-zero, enable TTY mode when it is available.
If zero, disable TTY mode in all cases.
Overrides the default, which is TTY mode %s.
DC_PROMPT
If an integer and non-zero, enable prompt when TTY mode is possible.
If zero, disable prompt in all cases.
Overrides the default, which is prompt %s.
DC_EXPR_EXIT
If an integer and non-zero, exit when expressions or expression files are
given on the command-line, and does not exit when an integer and zero.
Overrides the default, which is %s.
DC_DIGIT_CLAMP
If an integer and non-zero, clamp digits larger than or equal to the
current ibase when parsing numbers.
Overrides the default, which is %s.
