DESCRIPTION
The getopt function incrementally parses a command line argument list argv and returns the next known option character. An option character is known if it has been specified in the string of accepted option characters, optstring. The option string optstring may contain the following elements: individual characters, and characters followed by a colon to indicate an option argument is to follow. For example, an option string "" "x" " recognizes an option "-x", and an option string "" "x:" " recognizes an option and argument "-x argument". It does not matter to getopt if a following argument has leading white space.
On return from getopt, optarg points to an option argument, if it is anticipated, and the variable optind contains the index to the next argv argument for a subsequent call to getopt. The variable optopt saves the last known option character returned by getopt.
The variables opterr and optind are both initialized to 1. The optind variable may be set to another value before a set of calls to getopt in order to skip over more or less argv entries.
In order to use getopt to evaluate multiple sets of arguments, or to evaluate a single set of arguments multiple times, the variable optreset must be set to 1 before the second and each additional set of calls to getopt, and the variable optind must be reinitialized.
