GETSUBOPT(3) | Library Functions Manual | GETSUBOPT(3)

# NAME

`getsubopt` — get sub options from an argument

# SYNOPSIS

`#include <stdlib.h>`

extern char *suboptarg;

int
`getsubopt`(char **optionp, char * const *tokens, char **valuep);

# DESCRIPTION

The `getsubopt`() function parses a string containing tokens delimited by one or more tab, space, or comma (‘`,`’) characters. It is intended for use in parsing groups of option arguments provided as part of a utility command line.

The argument optionp is a pointer to a pointer to the string. The argument tokens is a pointer to a `NULL`-terminated array of pointers to strings.

The `getsubopt`() function returns the zero-based offset of the pointer in the tokens array referencing a string which matches the first token in the string, or -1 if the string contains no tokens or tokens does not contain a matching string.

If the token is of the form name=value, the location referenced by valuep will be set to point to the start of the “value” portion of the token.

On return from `getsubopt`(), optionp will be set to point to the start of the next token in the string, or the NUL at the end of the string if no more tokens are present. The comma, space, or tab character ending the token just parsed, and the equal sign separating name and value if any, are replaced with NUL bytes in the original *optionp input string. The external variable suboptarg will be set to point to the start of the current token, or `NULL` if no tokens were present. The argument valuep will be set to point to the value portion of the token, or `NULL` if no value portion was present.

# EXAMPLES

    char *tokens[] = {
    	#define	ONE	0
    		"one",
    	#define	TWO	1
    		"two",
    	NULL
    };

    ...

    extern char *optarg, *suboptarg;
    char *options, *value;

    while ((ch = getopt(argc, argv, "ab:")) != -1) {
    	switch (ch) {
    	case 'a':
    		/* process "a" option */
    		break;
    	case 'b':
    		options = optarg;
    		while (*options) {
    			switch (getsubopt(&options, tokens, &value)) {
    			case ONE:
    				/* process "one" sub option */
    				break;
    			case TWO:
    				/* process "two" sub option */
    				if (!value)
    					error("no value for two");
    				i = atoi(value);
    				break;
    			case -1:
    				if (suboptarg)
    					error("illegal sub option %s",
    					  suboptarg);
    				else
    					error("missing sub option");
    				break;
    			}
    		}
    		break;
    	}
    }

# SEE ALSO

getopt(3), strsep(3)

# STANDARDS

The `getsubopt`() function conforms to IEEE Std 1003.1-2008 (“POSIX.1”).

Allowing space and tab characters to separate tokens and the external variable suboptarg are extensions to that standard.

# HISTORY

The `getsubopt`() function first appeared in 4.3BSD-Net/2.

August 4, 2022 | Debian