getopt(3C)getopt(3C)NAMEgetopt(), optarg, opterr, optind, optopt - get option letter from argu‐
ment vector
SYNOPSISDESCRIPTION
returns the next option letter in argv (starting from that matches a
letter in optstring. argc and argv are the argument count and argument
array as passed to optstring is a string of recognized option charac‐
ters; if a character is followed by a colon, the option takes an argu‐
ment which may or may not be separated from it by whitespace.
is the index of the next element of the vector to be processed. It is
initialized to 1 by the system, and updates it when it finishes with
each element of
returns the next option character from argv that matches a character in
optstring, if there is one that matches. If the option takes an argu‐
ment, sets the variable to point to the option argument as follows:
· If the option was the last character in the string pointed to by
an element of argv, then contains the next element of argv, and is
incremented by 2. If the resulting value of is greater than or
equal to argc, this indicates a missing option argument, and
returns an error indication.
· Otherwise, points to the string following the option character in
that element of argv, and is incremented by 1.
If, when is called, is NULL, or the string pointed to by either does
not begin with the character or consists only of the character returns
−1 without changing If points to the string returns −1 after increment‐
ing
If encounters an option character that is not contained in optstring,
it returns the question-mark character. If it detects a missing option
argument, it returns the colon character if the first character of opt‐
string was a colon, or a question-mark character otherwise. In either
case, sets the variable to the option character that caused the error.
If the application has not set the variable to zero and the first char‐
acter of optstring is not a colon, also prints a diagnostic message to
standard error.
The special option can be used to delimit the end of the options; −1 is
returned, and is skipped.
RETURN VALUE
returns the next option character specified on the command line. A
colon is returned if detects a missing argument and the first character
of optstring was a colon
A question-mark is returned if encounters an option character not in
optstring or detects a missing argument and the first character of opt‐
string was not a colon
Otherwise, returns −1 when all command line options have been parsed.
EXTERNAL INFLUENCES
Locale
The category determines the interpretation of option letters as single
and/or multi-byte characters.
International Code Set Support
Single- and multibyte character code sets are supported.
ERRORS
fails under the following conditions:
[EILSEQ] An invalid multibyte character sequence was encountered
during option processing.
EXAMPLES
The following code fragment shows to process arguments for a command
that can take the mutually exclusive options and and the options and
both of which require arguments:
#include <stdio.h>
#include <unistd.h>
main (int argc, char *argv[])
{
int c;
int bflg, aflg, errflg;
extern char *optarg;
extern int optind, optopt;
.
.
.
while ((c = getopt(argc, argv, ":abf:o:")) != -1)
switch (c) {
case 'a':
if (bflg)
errflg++;
else
aflg++;
break;
case 'b':
if (aflg)
errflg++;
else {
bflg++;
bproc( );
}
break;
case 'f':
ifile = optarg;
break;
case 'o':
ofile = optarg;
break;
case ':': /* -f or -o without arguments */
fprintf(stderr, "Option -%c requires an argument\n",
optopt);
errflg++;
break;
case '?':
fprintf(stderr, "Unrecognized option: - %c\n",
optopt);
errflg++;
}
if (errflg) {
fprintf(stderr, "usage: . . . ");
exit (2);
}
for ( ; optind < argc; optind++) {
if (access(argv[optind], 4)) {
.
.
.
}
WARNINGS
Options can be any ASCII characters except colon question mark or null
SEE ALSOgetopt(1), thread_safety(5).
STANDARDS CONFORMANCEgetopt(3C)
