Install4J - Allow override of a bundled JRE in Unix Installer

install4j-manual.sh

# Allow override of Bundled JRE
#    Override can be set either via the INSTALL4J_JAVA_HOME_OVERRIDE environment variable or
#    by passing -manual <path> to the installer. The -manual arg will override the environment
#    variable if both are set. INSTALL4j_JAVA_HOME_OVERRIDE is provided if a savvy user looks 
#    up the Install4J documentation.
# 
# Instructions:
#    In your Unix Installer Media, select the "Installer Options" -> "Installer Custom Script"
#    option in the left pane. Select direct entry and copy/paste this script into the provided 
#    editor.
#
# Author: chrisisbeef 
# Version: 0.0.1

# Set this to the supported version of Java for your application
SUPPORTED_JRE_VERSION="1.7"

[ "$1" = "-manual" ] && shift && INSTALL4J_JAVA_HOME_OVERRIDE=$1

if [ ! -z "$INSTALL4J_JAVA_HOME_OVERRIDE" ]; then
   echo "Testing Override JRE at $INSTALL4J_JAVA_HOME_OVERRIDE"
   [ ! -f "$INSTALL4J_JAVA_HOME_OVERRIDE/bin/java" ] && echo "[!] No java found at $INSTALL4J_JAVA_HOME_OVERRIDE/bin" && INVALID_JAVA=true
   
   JAVA_VERSION_TMP=$($INSTALL4J_JAVA_HOME_OVERRIDE/bin/java -version 2>&1 | grep "java version" | cut -d"\"" -f2)
   [ -z $(echo $JAVA_VERSION_TMP | grep -q $SUPPORTED_JRE_VERSION && echo $?) ] && echo "[!] Invalid Java Version found: $JAVA_VERSION_TMP" && INVALID_JAVA=true
   if [ ! -z "$INVALID_JAVA" ]; then
      while true
      do
         read -p "Override JRE is not valid. Would you like to continue with the bundled JRE [Y/n]" USE_BUNDLED_JRE
         case $USE_BUNDLED_JRE in
            [Nn])
               echo "[!] No Valid JRE Available - Exiting"
               exit 1
               ;;
            *)
               break
               ;;
         esac
      done
   else
      echo "Using Override JRE ($JAVA_VERSION_TMP) at $INSTALL4J_JAVA_HOME_OVERRIDE"
      app_java_home=$INSTALL4J_JAVA_HOME_OVERRIDE
   fi
fi