how to detect a build error from ant/maven via a bash script?

mvn clean test
if [[ "$?" -ne 0 ]] ; then
  echo 'could not perform tests'; exit $rc
fi

• $? is a special shell variable that contains the exit code (whether it terminated successfully, or not) of the most immediate recently executed command.
• -ne stands for “not equal”. So here we are testing if the exit code from mvn clean is not equal to zero.