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How you can Set JAVA_HOME in Ubuntu Linux – Guide
If you are running Java programs on Ubuntu using Eclipse, Maven or Netbeans etc, you will need to set JAVA_HOME to your path. Otherwise, your system will complain that “the environment variable java_home is not set”.
in this beginner tutorial, I’ll show you the steps to correctly set up Java Home variable in Ubuntu. The steps should also be valid for most other Linux distributions.
The process consists of the following steps:
Step 1: Make sure the JDK is installed
The simplest way to check if the Java Development Kit (JDK) is installed on your Linux system is to run this command:
javac – version
The above command checks the Java compiler version. If installed, it will show the Java version.
check ubuntu java compiler
Java Compiler is installed
If the command shows an error like javac command not found, you will have to install the JDK.
Java compiler check on ubuntu
Java compiler not installed
If the Java Compiler is not installed on your system, install the Java Development Kit using this command:
sudo apt install default-jdk
This will install the default Java version on your current Ubuntu version. If you need some other specific version of Java, you will have to specify it when installing Java on Ubuntu.
After verifying that the Java Compiler is present on your system, it’s time to find its location.
Step 2: Get the location of the JDK executable (Java Compiler)
The executable is usually located in the /usr/lib/jvm directory. I won’t leave you alone for a guessing game. Instead, let’s find out the path to the Java executable.
Use the which command to get the location of the Java compiler executable:
The problem here is that the location it provides is actually a symbolic link. You will have to follow it a few times:
get java home ubuntu path
And when you find a path like / usr / lib / jvm / java-11-openjdk-amd64 / bin / javac, you remove / bin / javac from it to get something like / usr / lib / jvm / java-11- openjdk -amd64
An easier method is to follow the symbolic link and access the actual executable file directly using this command:
readlink -f `which javac` | sed “s: / bin / javac ::”
The readlink command follows a symbolic link. I used `around which java. This is called command substitution and replaces the command with its output. Sed is then used to replace /bin/javac with nothing and thus remove it altogether.
In my example, the location of the executable file is /usr/lib/jvm/java-11-openjdk-amd64. It might be different for you. Copy the correct path obtained with the above command to your system. You know, you can copy and paste into Ubuntu terminal.
Step 3: Set the JAVA_HOME variable
Now that you have the location, use it to set the JAVA_HOME environment variable:
export JAVA_HOME = / usr / lib / jvm / java-11-openjdk-amd64 / bin / java
Check the value of the JAVA_HOME directory:
define java home Ubuntu Linux
define java home Ubuntu Linux
Try running your program or project on the SAME TERMINAL and see if it works.
This is not over yet. The JAVA_HOME variable you just declared is temporary. If you close the terminal or start a new session, it will be empty again.
To set the JAVA_HOME variable ‘permanently’, you must add it to the bashrc file in your home directory.
You can use Nano editor to edit files in Linux terminal. If you don’t want this and use a simple copy and paste approach, use the following commands:
Come back up your bashrc file (in case you mess up, you can recover it):
cp ~ / .bashrc ~ / .bashrc.bak
Then use the echo command to append the export command used at the beginning of this section. Change the command below to use the correct path as displayed by your system on.
echo “export JAVA_HOME = / usr / lib / jvm / java-11-openjdk-amd64” >> ~ / .bashrc
Check that it was correctly added to the final of the file:
tail -3 ~ / .bashrc
The tail command above will show the last 3 lines of the specified file.
Here is all the output from the three commands above.
setting java home bashrc
Now, even if you log out or restart the system, the JAVA_HOME variable will still be set to the value you specified. That’s what you want, right?
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