Start now shell scripting ruby on rails after user created

Budget:15$ ,this is very quick job,please do not apply moe than [login to view URL] to have 5+ years of experience as System admin and writing shell scripts in Ubuntu OS. Write 2 lines of shell script to write for sudo add user and add text to configuration file in server once user has signup in ruby on rails application,should work in production mode .Communication should be quick. Looking for long term relationship followed bu other tasks. Happy bidding...