Install unrar command

Under Debian Linux, you need to type apt-get as follows to install unrar program:
# apt-get install unrar

If you are using Fedora core Linux then use yum command as follows (see discussion below):
# yum install unrar

If you are using FreeBSD, use:
# pkg_add -v -r unrar

If any of above, methods is not working for you, download binary package from official rarlab site:
$ cd /tmp
$ wget http://www.rarlab.com/rar/rarlinux-3.6.0.tar.gz

Untar file
$ tar -zxvf rarlinux-3.6.0.tar.gz

Both unrar and rar commands are located in rar sub-directory. Just go to rar directory:
$ cd rar
$ ./unrar

Now copy rar and unrar to /bin directory:
# cp rar unrar /bin