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+[#]: subject: "How to Set JAVA_HOME Variable in Ubuntu Linux Correctly"
+[#]: via: "https://itsfoss.com/set-java-home-ubuntu/"
+[#]: author: "Abhishek Prakash https://itsfoss.com/author/abhishek/"
+[#]: collector: "lujun9972"
+[#]: translator: " "
+[#]: reviewer: " "
+[#]: publisher: " "
+[#]: url: " "
+
+How to Set JAVA_HOME Variable in Ubuntu Linux Correctly
+======
+
+If you are [running Java programs on Ubuntu][1] using Eclipse, [Maven][2] or Netbeans etc, you’ll need to set JAVA_HOME to your path. Otherwise, your system will complain that “java_home environment variable is not set”.
+
+In this beginner’s tutorial, I’ll show the steps to correctly set Java Home variable on Ubuntu. The steps should be valid for most other Linux distributions as well.
+
+The process consists of these steps:
+
+  * Making sure Java Development Kit (JDK) is installed.
+  * Finding the correct location of JDK executable.
+  * Setting the JAVA_HOME variable and making the change permanent.
+
+
+
+### Step 1: Check if JDK is installed
+
+The simplest way to check if Java Development Kit (JDK) is installed on your Linux system is by running this command:
+
+```
+javac --version
+```
+
+The above command checks the version of Java compiler. If it is installed, it will show the Java version.
+
+![Java Compiler is installed][3]
+
+If the command shows an error like javac command not found, you’ll have to install JDK.
+
+![Java Compiler is not installed][4]
+
+If Java Compiler is not installed on your system, install Java Development Kit using this command:
+
+```
+sudo apt install default-jdk
+```
+
+This will install the default Java version in your current Ubuntu version. If you need some other specific Java version, you’ll have to specify it while [installing Java on Ubuntu][5].
+
+Once you have made sure that Java Compiler is present on your system, it’s time to find its location.
+
+### Step 2: Get the location of JDK executable (Java Compiler)
+
+The executable is usually located in the /usr/lib/jvm directory. I won’t left you on your own for a guessing game. Instead, let’s find out the path of the Java executable.
+
+[Use the which command][6] to get the location of Java Compiler executable:
+
+```
+which javac
+```
+
+The problem here is that the location it gives is actually a [symbolic link][7]. You’ll have to follow it a couple of times:
+
+![][8]
+
+An easier method is to follow the symbolic link and get to the actual executable file directly using this command:
+
+```
+readlink -f `which java`
+```
+
+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. So basically, the above command is equivalent to _readlink -f /usr/bin/java_ in this case.
+
+In my example, the location of the executable file is **/usr/lib/jvm/java-11-openjdk-amd64/bin/java**. It could be different for you. Copy the correct path you got from the above command in your system. You know, you can [copy paste in the Ubuntu terminal][9].
+
+### Step 3: Setting JAVA_HOME variable
+
+Now that you have got 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 JAVA_HOME directory:
+
+```
+echo $JAVA_HOME
+```
+
+![][10]
+
+Try to run your program or project in 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 JAVA_HOME variable ‘permanently’, you should add it to the bashrc file in your home directory.
+
+You can [use the Nano editor for editing files in the Linux terminal][11]. If you do not want that and take a simple copy-paste approach, use the following commands:
+
+Back up your bashrc file (in case you mess it, you can get it back):
+
+```
+cp ~/.bashrc ~/.bashrc.bak
+```
+
+Next, [use the echo command to append][12] the export command you used at the beginning of this section. _**Change the command below to use the correct path as displayed by your system in**_.
+
+```
+echo "export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64/bin/java" >> ~/.bashrc
+```
+
+Verify that it has been correctly added to the end of the file:
+
+```
+tail -3 ~/.bashrc
+```
+
+The above [tail command][13] will show the last 3 lines of the specified file.
+
+Here’s the entire output of the above three commands.
+
+![][14]
+
+Now, even if you exit the session or restart the system, the JAVA_HOME variable will still be set to the value you specified. That’s what you want, right?
+
+Do note that if you change the default Java version in the future, you’ll have to change the value of JAVA_HOME and point it to the correct executable path.
+
+I hope this tutorial not only helped you to set Java Home, it also taught you how you are doing it.
+
+If you are still facing issues or have any questions or suggestions, please let me know in the comments.
+
+--------------------------------------------------------------------------------
+
+via: https://itsfoss.com/set-java-home-ubuntu/
+
+作者：[Abhishek Prakash][a]
+选题：[lujun9972][b]
+译者：[译者ID](https://github.com/译者ID)
+校对：[校对者ID](https://github.com/校对者ID)
+
+本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
+
+[a]: https://itsfoss.com/author/abhishek/
+[b]: https://github.com/lujun9972
+[1]: https://itsfoss.com/run-java-program-ubuntu/
+[2]: https://maven.apache.org/
+[3]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2021/09/check-java-compiler-ubuntu.png?resize=750%2C310&ssl=1
+[4]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2021/09/java-compiler-check-ubuntu.png?resize=732%2C300&ssl=1
+[5]: https://itsfoss.com/install-java-ubuntu/
+[6]: https://linuxhandbook.com/which-command/
+[7]: https://linuxhandbook.com/symbolic-link-linux/
+[8]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2021/09/get-java-home-path-ubuntu.png?resize=800%2C283&ssl=1
+[9]: https://itsfoss.com/copy-paste-linux-terminal/
+[10]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2021/09/setting-java-home-ubuntu.png?resize=800%2C268&ssl=1
+[11]: https://itsfoss.com/nano-editor-guide/
+[12]: https://linuxhandbook.com/echo-command/
+[13]: https://linuxhandbook.com/tail-command/
+[14]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2021/09/set-java-home-bashrc-ubuntu.png?resize=786%2C348&ssl=1