Web3j provides a command-line tool distributed as a portable .jar. In a few steps, you can start using the web3j command line, so no installation is required. In your home folder. run wget https://github.com/web3j/web3j/releases/download/v3.4.0/web3j-3.4.0.tar.

Unzip the downloaded TAR file:

 tar  xvf web3j-3.4.0

Then add the resultant folder to the system's path:

 export PATH=$PATH:~/web3j-3.4.0/bin

You're all set. Now, you can create Ethereum accounts or generate wrapper classes for your smart contracts.