There are two flavor of JDK you can get from any Linux distros, OpenJDK or from Oracle. These software can be installed manually, assigning the static path on JAVA_HOME. What if you installed it directly from yum or apt, how can you assign the correct Java directory for a managed installation?
Note: This how-to assumes you’re using bash as your shell. Feel free to apply it based on what shell you’re using.
User Implementation
STEP 1
Open your .bashrc file using your favorite editor. In this case, I’m using vim.
vi ~/.bashrc
STEP 2
At the end of your .bashrc place the following snippets.
export JAVA_HOME=$(dirname $(dirname $(readlink -f $(which javac))))
Then save.
STEP 3
Source your .bashr and check if your JAVA_HOME‘s set.
source ~/.bashrc
printenv JAVA_HOME
Your JAVA_HOME should contain the directory of you JDK installation.
System-wide Implementation
Almost same with our previous steps, but instead of editing our .bashrc we’ll be creating a script file on /etc/profile.d
STEP 1
Create a script file on /etc/profile.d and open the file, or you can do both in one go. But for the sake of this tutorial will do the long one.
touch java.sh
vi java.sh
Note: If you’re not root, you have to sudo on the commands.
STEP 2
Place this on the file
#!/usr/local/env bash
export JAVA_HOME=$(dirname $(dirname $(readlink -f $(which javac))))
Then save.
STEP 3
Source the java.sh and check if JAVA_HOME‘s set. You can also logout then log back-in again to check if the script’s loaded.
source java.sh
printenv JAVA_HOME
Once done, make sure the output shows the location of your Java or JDK installation.