The installer for NexusPro uses Install4J. Although the Nexus documentation doesn’t explain how, you can script the installer by providing a response.varfile. I found this to be quite picky about order and arguments, the ones shown below are known to work in this specific order.

% bash ./nexus-pro-trial-installer-latest-unix.sh -varfile response.varfile -q -dir /home/builder/nexus -overwrite -splash

Boom! It installs without question. It should be available at http://localhost:8081/nexus/index.html

Example response file

#install4j response file for Sonatype Nexus Pro Trial 2.11.4-01
#Mon Nov 02 12:38:09 UTC 2015
nexus.evalGuideDir=/home/root/nexus-evalguide
sys.adminRights$Boolean=false
nexus.launchControl$Boolean=true
nexus.startService$Boolean=true
sys.programGroupDisabled$Boolean=false
sys.component.pro$Boolean=true
nexus.createDesktopLinks$Boolean=true
nexus.tmpDir=/root/.nexus-pro-trial/tmp
nexus.workDir=/root/.nexus-pro-trial
nexus.httpPort$Long=8081
sys.languageId=en
sys.installationDir=/root/nexus-pro-trial-2.11.4-01
nexus.openEvalGuide$Boolean=false
nexus.openAppUrl$Boolean=false
sys.symlinkDir=/usr/local/bin
sys.component.trial-config$Boolean=true
sys.component.trial-evalguide$Boolean=true

Good luck!