Mac shell java switching

.javapath

#!/bin/bash
# Put this .javapath file in your home directory with execute permission.
# Run it to create java dotfiles in your home directory to set up
#  PATH and JAVA_HOME for indicated java distros
# Source the resulting dotfiles to switch current JAVA

if (return 2>/dev/null)
then
  PATH=$(echo "$PATH" |
    awk -F: '{for (i=1;i<=NF;i++){print $i}}' |
    egrep -v 'j(dk|re)' |
    ( echo "$JAVA_HOME/bin"; cat ) |
    awk 'BEGIN {d=""} {printf("%s%s",d,$0);d=":"} END{printf "\n"}')
  export PATH
  echo "PATH=$PATH"
else
  jvms_root="/Library/Java/JavaVirtualMachines"
  cd "${jvms_root}"
  ls |
    (while read java
    do
      export java
      rcfile="${HOME}/.$( echo $java|sed -E '/\.j(re|dk)/s///')"
      (echo 'export JAVA_HOME='"$(find ${jvms_root}/${java} -name Home|head -1)";
        echo ". ~/.javapath";echo) > "${rcfile}"
      chmod ug+x "${rcfile}" && echo "${rcfile}"
    done)
fi