Jenkins: Run a shell command on all slaves using the Groovy console. https://stackoverflow.com/questions/26583979/run-a-remote-command-on-all-jenkins-slaves-via-masterss-script-console

run_command_on_all_slaves.groovy

import hudson.util.RemotingDiagnostics;

script = 'def proc = "ls -1 /media".execute(); proc.waitFor(); println proc.in.text';

for (slave in Jenkins.instance.slaves) {
  println slave.name;
  try {
    println RemotingDiagnostics.executeGroovy(script, slave.getChannel());
  } catch (all) {
    all.printStackTrace();
  }
}