To install Multichain in Linux, you first need to get Multichain files:
$ cd /tmp
$ wget https://www.multichain.com/download/multichain-2.0-beta-2.tar.gz
Now extract the download files:
$ tar -xvzf multichain-2.0-beta-2.tar.gz
And then move the files to /usr/local/bin
$ cd multichain-2.0-beta-2
$ sudo mv multichaind multichain-cli multichain-util /usr/local/bin
Multichain is installed.