Bash shell script: How to set JAVA_HOME environment variable

Using openSUSE, I downloaded the Oracle rpms for jdk1.6.0_24 and I want to set the java home environment variable to /usr/java/jdk1.6.0_24 but the /etc/alternatives system is unable to automatically detect this installed JDK. Update-alternatives , or whatever just doesn't find the jdk.

So, I want to detect the JAVA home manually in a BASH script.

If I run this command: sudo find /usr -name 'jdk1.6*' , I get this result:

/usr/java/jdk1.6.0_24

How do pipe that result into a environment variable? I want t开发者_C百科o do something like

#!/bin/bash
read in JAVA_HOME var from a file
if file doesnt exist
  sudo find /usr -name 'jdk1.6*' 
  prompt user for which jdk is correct
  set that choice to a variable 
  add the JDK to alternatives if it is missing
  save variable to a file and dont prompt next time
  set the alternatives java choice
fi
echo $JAVA_HOME

something like

#!/bin/bash
function validate_java_home {
    if [ -z ${JAVA_HOME} ]
    then
        # do something if the file doesn't provide ${JAVA_HOME}
    else 
        if [ ! -e ${JAVA_HOME} ]
        then
            # do something if the file provides a non existent ${JAVA_HOME}
        fi
    fi
}

if [ ! -e ${YOUR_FILE_NAME_CONTAINING_JAVA_HOME} ]
then
     JAVA_HOME_CANDIDATES=$(find /usr -name 'jdk1.6*')
     echo "Found the following candidates for JAVA_HOME, reply with the one you want then press return"
     echo ""
     echo $JAVA_HOME_CANDIDATES
     read USER_SUBMITTED_JAVA_HOME
     echo "You chose $USER_SUBMITTED_JAVA_HOME"
     JAVA_HOME=${USER_SUBMITTED_JAVA_HOME}
else
    . ${YOUR_FILE_NAME_CONTAINING_JAVA_HOME}
fi 
validate_java_home
export ${JAVA_HOME}

I haven't tested that but hopefully you get the gist (and I'd say using select as per glenn jackman's answer is more concise/friendly, didn't know that existed so I'm glad I read this Q!)

oldIFS="$IFS"
IFS=$'\n'
choices=( $(find /usr/java -type d -maxdepth 1 -print) )
select choice in "${choices[@]}"; do
  [[ "$choice" ]] && break
done
IFS="$oldIFS"
export JAVA_HOME="$choice"

Not sitting at a linux terminal, but this should get you going:

...
jdkpath=`sudo find /usr -name 'jdk1.6*'`
export JAVA_HOME=$jdkpath
...

Adjust as needed.

Based on Matt's answer , here is the script I am using:

#!/bin/bash
# JAVA_HOME script for RPM based java installations
# http://www.oracle.com/technetwork/java/javase/install-linux-64-rpm-138254.html
# examine and understand /etc/alternatives before you run this

cd $SITE_HOME

function set_java_home {
  if [ -z $JAVA_HOME ]; then
      echo "Using default value for JAVA_HOME: /usr/java/default"
      JAVA_HOME=/usr/java/default
  fi
  export -p JAVA_HOME
  echo $JAVA_HOME > java.home.config
  echo "JAVA_HOME variable set to $JAVA_HOME ."
}

if [ -f java.home.config ]; then
  JAVA_HOME=$(<java.home.config)
else
  JAVA_HOME_CANDIDATES=$(find /usr -type d -name 'jdk1.6*')
  echo "Found the following candidates for JAVA_HOME. Pick one: "
  echo "---"
  echo $JAVA_HOME_CANDIDATES
  echo "---"
  read USER_SUBMITTED_JAVA_HOME
  echo "You chose $USER_SUBMITTED_JAVA_HOME ."
  JAVA_HOME=${USER_SUBMITTED_JAVA_HOME}
fi
# Set the variable
set_java_home