getsubopt(3C) getsubopt(3C)
NAME
getsubopt() - parse suboptions from a string.
SYNOPSIS
DESCRIPTION
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 possible 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 suboption, updates to point to the null at the end of the string, otherwise 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-terminated 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 != ' ') {
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 ALSO
getopt(3C), thread_safety(5).
STANDARDS CONFORMANCE
getsubopt(3C)