2 * *****************************************************************************
4 * SPDX-License-Identifier: BSD-2-Clause
6 * Copyright (c) 2018-2020 Gavin D. Howard and contributors.
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36 usage: %s [options] [file...]
38 dc is a reverse-polish notation command-line calculator which supports unlimited
39 precision arithmetic. For details, use `man %s`.
41 This dc is (mostly) compatible with the FreeBSD dc and the GNU dc. See the
42 FreeBSD man page (https://www.unix.com/man-page/FreeBSD/1/dc/) and the GNU dc
43 manual (https://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html) for
46 This dc has a few differences from the two above:
48 1) When printing a byte stream (command "P"), this bc follows what the FreeBSD
50 2) This dc implements the GNU extensions for divmod ("~") and modular
52 3) This dc implements all FreeBSD extensions, except for "J" and "M".
53 4) This dc does not implement the run command ("!"), for security reasons.
54 5) Like the FreeBSD dc, this dc supports extended registers. However, they are
55 implemented differently. When it encounters whitespace where a register
56 should be, it skips the whitespace. If the character following is not
57 a lowercase letter, an error is issued. Otherwise, the register name is
58 parsed by the following regex:
62 This generally means that register names will be surrounded by whitespace.
66 l idx s temp L index S temp2 < do_thing
68 Also note that, unlike the FreeBSD dc, extended registers are not even
69 parsed unless the "-x" option is given. Instead, the space after a command
70 that requires a register name is taken as the register name.
74 -e expr --expression=expr
76 Run "expr" and quit. If multiple expressions or files (see below) are
77 given, they are all run. After running, dc will exit.
81 Run the dc code in "file" and exit. See above.
85 Print this usage message and exit.
89 Put dc into interactive mode. See the man page for more details.
93 Disable the prompt in interactive mode.
97 Print version and copyright and exit.
99 -x --extended-register
101 Enable extended register mode.