GETOPT(S) XENIX System V GETOPT(S)
Name
getopt - Gets option letter from argument vector.
Syntax
#include <stdio.h>
int getopt (argc, argv, optstring)
int argc;
char *argv[];
char *optstring;
extern char *optarg;
extern int optind, opterr;
Description
getopt returns the next option letter in argv that matches a
letter in optstring. optstring is a string of recognized
option letters; if a letter is followed by a colon, the
option is expected to have an argument that may or may not
be separated from it by whitespace. optarg is set to point
to the start of the option argument on return from getopt.
getopt places in optind the argv index of the next argument
to be processed. Because optind is external, it is normally
initialized to zero automatically before the first call to
getopt.
When all options have been processed (i.e., up to the first
nonoption argument), getopt returns EOF. The special option
-- may be used to delimit the end of the options; EOF will
be returned, and -- will be skipped.
Diagnostics
getopt prints an error message on stderr and returns a
question mark (?) when it encounters an option letter not
included in optstring. This error message may be disabled
by setting opterr to zero.
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GETOPT(S) XENIX System V GETOPT(S)
Examples
The following code fragment shows how one might process the
arguments for a command that can take the mutually exclusive
options a and b, and the options f and o, both of which
require arguments:
main (argc, argv)
int argc;
char **argv;
{
int c;
extern int optind;
extern char *optarg;
.
.
.
while ((c = getopt (argc, argv, "abf:o:")) != EOF)
switch (c) {
case 'a':
if (bflg)
errflg++;
else
aflg++;
break;
case 'b':
if (aflg)
errflg++;
else
bproc();
break;
case 'f':
ifile = optarg;
break;
case 'o':
ofile = optarg;
bufsiza = 512;
break;
case '?':
errflg++;
}
if (errflg) {
fprintf (stderr, "usage: . . . ");
exit (S);
}
for( ; optind < argc; optind++) {
if (access (argv[optind], 4)) {
.
.
.
}
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