GETSUBOPT(3) Linux Programmer's Manual GETSUBOPT(3)
getsubopt - parse suboption arguments from a string
int getsubopt(char **optionp, char * const *tokens, char **valuep);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_XOPEN_SOURCE >= 500
|| /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
getsubopt() parses the list of comma-separated suboptions provided in optionp. (Such a suboption list is typically produced when getopt(3)
is used to parse a command line; see for example the -o option of mount(8).) Each suboption may include an associated value, which is sep-
arated from the suboption name by an equal sign. The following is an example of the kind of string that might be passed in optionp:
The tokens argument is a pointer to a NULL-terminated array of pointers to the tokens that getsubopt() will look for in optionp. The
tokens should be distinct, null-terminated strings containing at least one character, with no embedded equal signs or commas.
Each call to getsubopt() returns information about the next unprocessed suboption in optionp. The first equal sign in a suboption (if any)
is interpreted as a separator between the name and the value of that suboption. The value extends to the next comma, or (for the last sub-
option) to the end of the string. If the name of the suboption matches a known name from tokens, and a value string was found, getsubopt()
sets *valuep to the address of that string. The first comma in optionp is overwritten with a null byte, so *valuep is precisely the "value
string" for that suboption.
If the suboption is recognized, but no value string was found, *valuep is set to NULL.
When getsubopt() returns, optionp points to the next suboption, or to the null byte ('