I know how to open .rar file under Linux, but how do you open .rar file under Apple OS X UNIX using command line and GUI tools options?

The unrar command or gui tools are not supported out of the box. Use the following instructions install the same:

unrar Command Line Tool

You need to download unrar by visiting this page and look for OS X version. Alternativly, you can open the terminal and type the following command to download the same:

cd /tmp
curl -o output.tar.gz http://www.rarlab.com/rar/rarosx-3.9.3.tar.gz

Untar the tar ball, enter:

tar -zxvf output.tar.gz

Sample outputs:

sudo cp -v /tmp/rar/{rar,unrar} /bin
rm -rf /tmp/rar

Sample outputs:

How Do I Use Unrar Command Line?

You can use the unrar command as follows:

Task: Extract Files

The syntax is as follows to open or unrar file in current directory:

unrar e file.rar 
ls -l

Task: List (l) File Inside Rar Archive

unrar l file.rar

Task: To Extract (x) Files With Full Path

unrar x file.rar

Task: To Test (t) Integrity Of Archive

unrar t file.rar

To see all support command line options type:
unrar | less

GUI App: The Unarchiver

You can use “The Unarchiver” is free software and it is a much more capable replacement for “BOMArchiveHelper.app”, the built-in archive unpacker program in Mac OS X. The Unarchiver is designed to handle many more formats than BOMArchiveHelper, and to better fit in with the design of the Finder. Supported file formats include Zip, Tar-GZip, Tar-BZip2, RAR, 7-zip, LhA, StuffIt and many other more and less obscure formats. The goal is to make The Unarchiver able to extract anything you give it.
=> Download The Unarchiver