getsubopt(3C)getsubopt(3C)NAMEgetsubopt() - parse suboptions from a string.
SYNOPSISDESCRIPTION
parses suboptions in a flag argument that were initially parsed by (see
getopt(3C)). These suboptions are separated by commas, and may consist
of either a single token, or a token-value pair separated by an equal
sign. Because commas delimit suboptions in the option string, they are
not allowed to be part of the suboption or the value of a suboption.
Similarly, because the equal sign separates a token from its value, a
token must not contain an equals sign. An example command that uses
this syntax is allows parameters to be specified with the switch as
follows:
In this example there are four suboptions: and the last of which has an
associated value of 1024.
takes the address of a pointer to the option string, a vector of possi‐
ble tokens, and the address of a value string pointer. It returns the
index of the token that matched the suboption in the input string or −1
if there was no match. If the option string at contains only one sub‐
option, updates to point to the null at the end of the string, other‐
wise it isolates the suboption by replacing the comma separator with a
null, and updates to point to the start of the next suboption. If the
suboption has an associated value, updates to point to the value of the
first character. Otherwise it sets to NULL.
The token vector is organized as a series of pointers to NULL-termi‐
nated strings. The end of the token vector is identified by NULL.
When returns, if is not NULL then the suboption processed included a
value. The calling program can use this information to determine if
the presence or lack of a value for this suboption is an error.
Additionally, when fails to match the suboption with the tokens in the
tokens array, the calling program should decide if this is an error, or
if the unrecognized option should be passed on to another program.
EXTERNAL INFLUENCES
Locale
The category determines the interpretation of option letters as single
and/or multi-byte characters.
International Code Set Support
Single- and multi-byte character code sets are supported with the
exception of multi-byte-character file names.
EXAMPLES
The following code fragment shows how options can be processed to the
command by using
char *myopts[] = {
#define READONLY 0
"ro",
#define READWRITE 1
"rw",
#define WRITESIZE 2
"wsize",
#define READSIZE 3
"rsize",
NULL};
main (int argc, char **argv)
{
int sc, c, errflag;
char *options, *value;
extern char *optarg;
extern int optind;
.
.
.
while ((c = getopt(argc, argv, "abf:o:")) != EOF)
switch (c) {
case 'a': /* process 'a' option */
break;
case 'b': /* process 'b' option */
break;
case 'f':
ofile = optarg;
break;
case '?':
errflag++;
break;
case 'o':
options = optarg;
while (*options != '\0') {
switch(getsubopt(&options, myopts, &value)) {
case READONLY: /* process ro option */
break;
case READWRITE: /* process rw option */
break;
case WRITESIZE: /* process wsize option */
if (value == NULL) {
error_no_arg();
errflag++;
}
else
write_size = atoi(value);
break;
case READSIZE: /* process rsize option */
if (value == NULL) {
error_no_arg();
errflag++;
}
else
read_size = atoi(value);
break;
default:
/* process unknown token */
error_bad_token(value);
errflag++;
break;
}
}
break;
}
}
if (errflg) {
fprintf(stderr, "usage: . . . ");
exit (2);
}
for ( ; optind < argc; optind++) {
/* process remaining arguments */
.
.
.
}
SEE ALSOgetopt(3C), thread_safety(5).
STANDARDS CONFORMANCEgetsubopt(3C)
