Command options

Most commands accept numerous "options". An option can be introduced with an "-" (dash). For example:

dir -l

shows me the listing of the current directory but in a long format (the default format is "short"). Multiple options can be introduced in two, equivalent ways:

dir -l -a

or

dir -la

Either of the above commands will show me the listing of the current directory in the long file format (option -l), and include all files in the listing, i.e., also the hidden files (option -a).

Most popular options are marked with one letter. This follows the traditional UNIX way of invoking options. There is also a new style, which looks like this:

dir --help

Here, a single option is more than one character long, and it must be introduced with two dashes. The above command displays a brief help for the dir command, including the listing of all options. Because there are so many of those (more than a screen-full), I would probably do:

dir --help | more