getopt(3)getopt(3)Namegetopt - get 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
The subroutine returns the next option letter in argv that matches a
letter in optstring. The 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 white
space. The optarg is set to point to the start of the option argument
on return from
The function places in optind the argv index of the next argument to be
processed. The external variable optind is automatically initialized
to 1 before the first call to
When all options have been processed (that is, up to the first non-
option argument), returns EOF. The special option -- may be used to
delimit the end of the options; EOF will be returned, and -- will be
skipped.
Diagnostics
The function prints an error message on stderr and returns a question
mark (?) when it encounters an option letter that is not included in
optstring. Setting opterr to 0 disables this error message.
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:
#include <stdio.h>
main (argc, argv)
int argc;
char ∗∗argv;
{
int c;
extern int optind, opterr;
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 (2);
}
for ( ; optind < argc; optind++) {
if (access (argv[optind], 4)) {
.
.
.
}
See Alsogetopt(1)getopt(3)
