To open or extract a RAR file under Linux or UNIX, you will need to use a program called unrar. This program is available in the repositories of most Linux and UNIX distributions, and can be installed using the package manager of your operating system.
On a Debian-based system, use the following command to install unrar:
sudo apt-get install unrar
On a Red Hat-based system, use the following command:
sudo yum install unrar
On a FreeBSD system, use the following command:
sudo pkg install unrar
Once unrar is installed, you can use it to extract the contents of a RAR file by running the following command:
unrar x /path/to/myfile.rar
This will extract the contents of the RAR file to the current directory. If you want to extract the contents to a different directory, use the following command:
unrar x /path/to/myfile.rar /path/to/extract/to/
You can also use unrar to view the contents of a RAR file without extracting it by using the l flag instead of the x flag:
unrar l /path/to/myfile.rar
This will list the contents of the RAR file, including the names and sizes of the files it contains.
Keep in mind that unrar is only capable of extracting RAR files that are not password-protected. If you need to extract a password-protected RAR file, you will need to use a program that can handle password-protected archives, such as p7zip.