Question

For example, I want to know what -r does in terminal. I can’t easily find any documentation but I assume in terminal there must be way to have a command explained. I tried info [-r] and help -r, but these combinations haven’t worked. I’m sure it is very simple. Thanks.

Answer 1

Each command-line tool supports different options.
There is no standardization, even if a lot of commands implement the same arguments for the same actions (as -r).

So you need to get help on a specific command.

You can do it with the man command, to get the complete manual of the command:

man [COMMAND]

Like:

man ls

A lot of commands also implements the --help or -h arguments, for a shorter help dialog.