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Diffstat (limited to 'man/man3/arg.3')
| -rw-r--r-- | man/man3/arg.3 | 124 |
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diff --git a/man/man3/arg.3 b/man/man3/arg.3 new file mode 100644 index 00000000..9036cdbc --- /dev/null +++ b/man/man3/arg.3 @@ -0,0 +1,124 @@ +.TH ARG 3 +.SH NAME +ARGBEGIN, ARGEND, ARGC, ARGF, EARGF, arginit, argopt \- process option letters from argv +.SH SYNOPSIS +.B #include <u.h> +.br +.B #include <libc.h> +.PP +.nf +.B ARGBEGIN { +.B char *ARGF(); +.B char *EARGF(code); +.B Rune ARGC(); +.B } ARGEND +.PP +.B extern char *argv0; +.SH DESCRIPTION +These macros assume the names +.I argc +and +.I argv +are in scope; see +.IR exec (2). +.I ARGBEGIN +and +.I ARGEND +surround code for processing program options. +The code +should be the cases of a C switch on +option characters; +it is executed once for each option character. +Options end after an argument +.BR -- , +before an argument +.BR - , +or before an argument that doesn't begin with +.BR - . +.PP +The function macro +.I ARGC +returns the current option character, as an integer. +.PP +The function macro +.I ARGF +returns the current option argument: +a pointer to the rest of the option string if not empty, +or the next argument in +.I argv +if any, or 0. +.I ARGF +must be called just once for each option +that takes an argument. +The macro +.I EARGF +is like +.I ARGF +but instead of returning zero +runs +.I code +and, if that returns, calls +.IR abort (2). +A typical value for +.I code +is +.BR usage() , +as in +.BR EARGF(usage()) . +.PP +After +.IR ARGBEGIN , +.I argv0 +is a copy of +.BR argv[0] +(conventionally the name of the program). +.PP +After +.IR ARGEND , +.I argv +points at a zero-terminated list of the remaining +.I argc +arguments. +.SH EXAMPLE +This C program can take option +.B b +and option +.BR f , +which requires an argument. +.IP +.EX +.ta \w'12345678'u +\w'12345678'u +\w'12345678'u +\w'12345678'u +\w'12345678'u +#include <u.h> +#include <libc.h> +void +main(int argc, char *argv[]) +{ + char *f; + print("%s", argv[0]); + ARGBEGIN { + case 'b': + print(" -b"); + break; + case 'f': + print(" -f(%s)", (f=ARGF())? f: "no arg"); + break; + default: + print(" badflag('%c')", ARGC()); + } ARGEND + print(" %d args:", argc); + while(*argv) + print(" '%s'", *argv++); + print("\en"); + exits(nil); +} +.EE +.PP +Here is the output from running the command +.B +prog -bffile1 -r -f file2 arg1 arg2 +.IP +.B +prog -b -f(file1) badflag('r') -f(file2) 2 args: 'arg1' 'arg2' +.PP +.SH SOURCE +.B /sys/include/libc.h |