Getopt is a group of functions which can be used to find command
line options.
Command line options come in two flavors: long and short. The short ones
consists of a dash followed by a character (-t), the long ones
consist of two dashes followed by a string of text (--test).
The short options can also be combined, which means that you can write
-tda instead of -t -d -a.
Options can also require arguments, in which case they cannot be
combined. To write an option with an argument you write
-t argument or -targument or
--test=argument.