unrar ?

[exrector]

******r@MacBook-Pro-A Extract % ./install_extract.sh
Downloading extract.sh...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  2908  100  2908    0     0  11740      0 --:--:-- --:--:-- --:--:-- 11773
Error: The following required utilities are missing:
 - unrar
Please install them before continuing.

Could you clarify which unrar and a link to it? There are too many options offered by google.
Thanks