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Check How you can Set JAVA_HOME in Ubuntu Linux
If you are running Java programs on Ubuntu using Eclipse, Maven or Netbeans etc, you will need to set JAVA_HOME in your path. Otherwise your system will complain that “java_home environment variable is not set”.
In this beginner tutorial, I will show the steps to properly set the Java startup variable in Ubuntu. The steps should also apply to most other Linux distributions.
The process consists of these steps:
- Make sure the Java Development Kit (JDK) is installed.
- Find the correct location of the JDK executable.
- Set the JAVA_HOME variable and make the change permanent.
Step 1: check if JDK is installed
The easiest way to check if the Java Development Kit (JDK) is installed on your Linux system is to run this command:
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 JDK.
Java compiler check on ubuntu
Java compiler is not installed
If the Java compiler is not installed on your system, install the Java development kit with this command:
sudo apt install default-jdk
This will install the default version of Java on your current version of Ubuntu. If you need any other specific version of Java, you will need to specify it when installing Java on Ubuntu.
Once you have made sure that the Java Compiler is present on your system, it is 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 of the Java executable.
Use the which command to get the location of the Java compiler executable:
The problem here is that the location you give is actually a symbolic link. You will have to follow it a couple of times:
get java ubuntu boot path
And when you find a path like / usr / lib / jvm / java-11-openjdk-amd64 / bin / javac, remove the / bin / javac to get something like / usr / lib / jvm / java-11- openjdk-amd64
An easier method is to follow the symbolic link and get to the actual executable file directly using this command:
readlink -f `which javac` | sed “s: / bin / javac ::”
The readlink command follows a symbolic link. I have used `around which java. This is called command substitution, and it replaces the command with its output. Sed is used to replace / bin / javac with nothing and thus remove it entirely.
In my example the executable file location is / usr / lib / jvm / java-11-openjdk-amd64. It could be different for you. Copy the correct path you got from the above command on your system. You know, you can copy paste in Ubuntu terminal.
Step 3: Setting 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:
echo $ JAVA_HOME
set java home ubuntu linux
set 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 need to add it to the bashrc file in your home directory.
You can use the Nano editor to edit files in the Linux terminal. If you don’t want that and take a simple copy and paste approach, use the following commands:
Make a backup of your bashrc file (in case you mess it up, you can get it back):
cp ~ / .bashrc ~ / .bashrc.bak
Then use the echo command to add the export command you used at the beginning of this section. Change the command below to use the correct path as shown by your system in.
echo “export JAVA_HOME = / usr / lib / jvm / java-11-openjdk-amd64” >> ~ / .bashrc
Verify that it was correctly added to the end of the file:
queue -3 ~ / .bashrc
The above queue command will display the last 3 lines of the specified file.
Here is the full output of the three commands above.
setting java home bashrc
Now, even if you log out or reboot 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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