10564b1175
groff 1.23.0 added .MR to its -man macro package. The NEWS file states
that the inclusion of the macro "was prompted by its introduction to
Plan 9 from User Space's troff in August 2020." From d32deab it seems
that the name for Plan 9 from User Space's implementation was suggested
by groff maintainer G. Brandon Robinson.
Not sure if the intention was to make these definitions compatible, but
it would be nice if they were.
Currently, Plan 9 from User Space's .MR expects its second argument to
be parenthesized. groff's .MR does not. This results in extra
parentheses appearing in manual references when viewing Plan 9 from User
Space's manual pages on a system using groff.
125 lines
2.1 KiB
Groff
125 lines
2.1 KiB
Groff
.TH ARG 3
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.SH NAME
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ARGBEGIN, ARGEND, ARGC, ARGF, EARGF, arginit, argopt \- process option letters from argv
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.SH SYNOPSIS
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.B #include <u.h>
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.br
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.B #include <libc.h>
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.PP
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.nf
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.B ARGBEGIN {
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.B char *ARGF();
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.B char *EARGF(code);
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.B Rune ARGC();
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.B } ARGEND
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.PP
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.B extern char *argv0;
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.SH DESCRIPTION
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These macros assume the names
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.I argc
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and
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.I argv
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are in scope; see
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.MR exec 3 .
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.I ARGBEGIN
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and
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.I ARGEND
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surround code for processing program options.
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The code
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should be the cases of a C switch on
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option characters;
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it is executed once for each option character.
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Options end after an argument
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.BR -- ,
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before an argument
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.BR - ,
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or before an argument that doesn't begin with
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.BR - .
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.PP
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The function macro
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.I ARGC
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returns the current option character, as an integer.
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.PP
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The function macro
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.I ARGF
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returns the current option argument:
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a pointer to the rest of the option string if not empty,
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or the next argument in
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.I argv
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if any, or 0.
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.I ARGF
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must be called just once for each option
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that takes an argument.
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The macro
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.I EARGF
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is like
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.I ARGF
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but instead of returning zero
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runs
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.I code
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and, if that returns, calls
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.MR abort 3 .
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A typical value for
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.I code
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is
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.BR usage() ,
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as in
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.BR EARGF(usage()) .
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.PP
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After
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.IR ARGBEGIN ,
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.I argv0
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is a copy of
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.BR argv[0]
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(conventionally the name of the program).
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.PP
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After
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.IR ARGEND ,
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.I argv
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points at a zero-terminated list of the remaining
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.I argc
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arguments.
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.SH EXAMPLE
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This C program can take option
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.B b
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and option
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.BR f ,
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which requires an argument.
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.IP
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.EX
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.ta \w'12345678'u +\w'12345678'u +\w'12345678'u +\w'12345678'u +\w'12345678'u
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#include <u.h>
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#include <libc.h>
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void
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main(int argc, char *argv[])
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{
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char *f;
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print("%s", argv[0]);
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ARGBEGIN {
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case 'b':
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print(" -b");
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break;
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case 'f':
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print(" -f(%s)", (f=ARGF())? f: "no arg");
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break;
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default:
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print(" badflag('%c')", ARGC());
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} ARGEND
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print(" %d args:", argc);
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while(*argv)
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print(" '%s'", *argv++);
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print("\en");
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exits(nil);
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}
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.EE
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.PP
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Here is the output from running the command
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.B
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prog -bffile1 -r -f file2 arg1 arg2
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.IP
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.B
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prog -b -f(file1) badflag('r') -f(file2) 2 args: 'arg1' 'arg2'
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.PP
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.SH SOURCE
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.B \*9/include/libc.h
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