TH ARG 2
SH NAME
ARGBEGIN, ARGEND, ARGC, ARGF, EARGF \- 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
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
SH SEE ALSO
IR getflags (8)
