GETOPT(3) GETOPT(3)
NAME
getopt - get option letter from argv
SYNOPSIS
int getopt (argc, argv, optstring)
int argc;
char **argv;
char *optstring;
extern char *optarg;
extern int optind;
extern int 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, which may or may not
be separated from it by white space. Optarg is set to point
to the start of the option argument, if any.
Optind, initially 1, holds the index in argv of the next
argument to be processed. When opterr is nonzero (the
default state), errors cause diagnostic messages.
Option letters appear in nonempty clusters preceded by -.
The special option `--' may be used to mark the end of the
options.
EXAMPLES
This fragment processes arguments for a command that can
take option a and option f, which requires an argument.
main (argc, argv) char **argv;
{
int c, errflg = 0;
extern int optind;
extern char *optarg, *ifile;
while((c = getopt(argc, argv, "af:")) != -1)
switch (c){
case 'a': aflg=1; break;
case 'f': ifile = optarg; break;
case '?': errflg=1; break;
}
if(errflg){
fprintf(stderr, "usage: . . . ");
exit(2);
}
for( ; optind < argc; optind++){
if(access(argv[optind], 4)){
GETOPT(3) GETOPT(3)
...
}
}
...
}
SEE ALSO
getflags(3)
DIAGNOSTICS
When all options have been processed, -1 is returned; optind
refers to the first non-option argument.
When getopt encounters an option letter not included in
optstring or finds an option argument missing, it prints a
diagnostic on stderr under control of opterr and returns a
question mark `?'.