[java] How to set JAVA_HOME in Linux for all users

I am new to Linux system and there seem to be too many Java folders.

java -version gives me:

• java version "1.7.0_55"
• OpenJDK Runtime Environment (rhel-2.4.7.1.el6_5-x86_64 u55-b13)
• OpenJDK 64-Bit Server VM (build 24.51-b03, mixed mode)

When I am trying to build a Maven project , I am getting error:

Error: JAVA_HOME is not defined correctly.
We cannot execute /usr/java/jdk1.7.0_05/bin/java

Could you please tell me which files I need to modify for root as well as not-root user and where exactly is java located?

None of the other answers were "sticking" for me in RHEL 7, even setting JAVA_HOME and PATH directly in /etc/profile or ~/.bash_profile would not work. Each time I tried to check if JAVA_HOME was set, it would come up blank:

$ echo $JAVA_HOME
    (<-- no output)

What I had to do was set up a script in /etc/profile.d/jdk_home.sh:

#!/bin/sh
export JAVA_HOME=/opt/ibm/java-x86_64-60/
export PATH=$JAVA_HOME/bin:$PATH

I initially neglected the first line (the #!/bin/sh), and it won't work without it.

Now it's working:

$ echo $JAVA_HOME
/opt/ibm/java-x86_64-60/

Posting as answer, as I don't have the privilege to comment.

Point to note: follow the accepted answer posted by "That Dave Guy".

After setting the variables, make sure you set the appropriate permissions to the java directory where it's installed.

chmod -R 755 /usr/java

Doing what Oracle does (as a former Sun Employee I can't get used to that one)

ln -s latestJavaRelease /usr/java/default
Where latestJavaRelease is the version that you want to use

then export JAVA_HOME=/usr/java/default

Use SDKMAN sdkman.io to switch btw. your sdk's.

It sets the JAVA_HOME for you.

Probably a good idea to source whatever profile you edit to save having to use a fresh login.

either: source /etc/ or . /etc/

Where is whatever profile you edited.

Step 1 - check the current java version by "echo $JAVA_HOME"

Step 2 - vim /etc/profile

Step 3 - At the end of file you will find export JAVA_HOME, we need to provide the new path here, make sure that it is not relative.

Step 4 - Save and exit :wq

Step 5 - "source /etc/profile/", this would execute the change

Step 6 - Again do a echo $JAVA_HOME - change would have been reflected.

On Linux I add this line to my ~/.profile:

export JAVA_HOME=$(readlink -ze /usr/bin/javac | xargs -0 dirname -z | xargs -0 dirname)

The answer is given previous posts is valid. But not one answer is complete with respect to:

1. Changing the /etc/profile is not recommended simply because of the reason (as stated in /etc/profile):

• It's NOT a good idea to change this file unless you know what you are doing. It's much better to create a custom.sh shell script in /etc/profile.d/ to make custom changes to your environment, as this will prevent the need for merging in future updates.*

2. So as stated above create /etc/profile.d/custom.sh file for custom changes.

3. Now, to always keep updated with newer versions of Java being installed, never put the absolute path, instead use:

#if making jdk as java home

export JAVA_HOME=$(readlink -f /usr/bin/javac | sed "s:/bin/javac::")

OR

#if making jre as java home

export JAVA_HOME=$(readlink -f /usr/bin/java | sed "s:/bin/java::")

4. And remember to have #! /bin/bash on the custom.sh file

While we are up to setting JAVA_HOME, let me share some benefits of setting JAVA_HOME or any other environment variable:

1) It's easy to upgrade JDK without affecting your application startup and config file which points to JAVA_HOME. you just need to download new version and make sure your JAVA_HOME points to new version of Java. This is best benefit of using environment variable or links.

2) JAVA_HOME variable is short and concise instead of full path to JDK installation directory.

3) JAVA_HOME variable is platform independence i.e. if your startup script uses JAVA_HOME then it can run on Windows and UNIX without any modification, you just need to set JAVA_HOME on respective operating system.

Read more: http://javarevisited.blogspot.com/2012/02/how-to-set-javahome-environment-in.html#ixzz4BWmaYIjH

You could use /etc/profile or better a file like /etc/profile.d/jdk_home.sh

export JAVA_HOME=/usr/java/jdk1.7.0_05/

You have to remember that this file is only loaded with new login shells.. So after bash -l or a new gnome-session and that it doesn't change with new Java versions.

For all users, I would recommend placing the following line in /etc/profile

export JAVA_HOME=$(readlink -f /usr/bin/javac | sed "s:/bin/javac::")

This will update dynamically and works well with the alternatives system. Do note though that the update will only take place in a new login shell.

All operational steps(finding java, parent dir, editing file,...) one solution

zFileProfile="/etc/profile"
zJavaHomePath=$(readlink -ze $(which java) | xargs -0 dirname | xargs -0 dirname)
echo $zJavaHomePath

echo "export JAVA_HOME=\"${zJavaHomePath}\"" >> $zFileProfile
echo "export PATH=\$PATH:\$JAVA_HOME/bin" >> $zFileProfile

Result:

# tail -2 $zFileProfile
export JAVA_HOME="/usr/lib/jvm/java-11-openjdk-11.0.7.10-1.el8_1.x86_64"
export PATH=$PATH:$JAVA_HOME/bin

Explanation:

1) Let's break the full command into pieces

$(readlink -ze $(which java) | xargs -0 dirname | xargs -0 dirname)

2) Find java path from java command

# $(which java)
"/usr/bin/java"

3) Get relative path from symbolic path

# readlink -ze /usr/bin/java
"/usr/lib/jvm/java-11-openjdk-11.0.7.10-1.el8_1.x86_64/bin/java"

4) Get parent path of /usr/lib/jvm/java-11-openjdk-11.0.7.10-1.el8_1.x86_64/bin/java

# readlink -ze /usr/bin/java | xargs -0 dirname
"/usr/lib/jvm/java-11-openjdk-11.0.7.10-1.el8_1.x86_64/bin"

5) Get parent path of /usr/lib/jvm/java-11-openjdk-11.0.7.10-1.el8_1.x86_64/bin/

# readlink -ze /usr/bin/java | xargs -0 dirname | xargs -0 dirname
"/usr/lib/jvm/java-11-openjdk-11.0.7.10-1.el8_1.x86_64"

Copy the bin file path you installed

YOUR PATH

open terminal and edit environment file by typing following command,

sudo nano /etc/environment

In this file, add the following line (replacing YOUR_PATH by the just copied path):

JAVA_HOME="YOUR_PATH"

That should be enough to set the environment variable. Now reload this file:

source /etc/environment

now test it by executing:

echo $JAVA_HOME

open kafka-run-class.sh with sudo to write

you can find kafka-run-class.sh in your kafka folder : kafka/bin/kafka-run-class.sh

check for these lines

Modify the JAVA variable in the else part to point to the java executable in your java/bin. like JAVA="$JAVA_HOME/java"

1...Using the short cut Ctlr + Alt + T to open terminal

2...Execute the below command:

echo export JAVA_HOME='$(readlink -f /usr/bin/javac | sed "s:/bin/javac::")' | sudo tee /etc/profile.d/jdk_home.sh > /dev/null

3...(Recommended) Restart your VM / computer. You can use source /etc/source if don't want to restart computer

4...Using the short cut Ctlr + Alt + T to open terminal

5...Verified JAVA_HOME installment with

echo $JAVA_HOME

One-liner copy from flob, credit to them

It's Very easy to set a path in Linux. Do as follows :

Step-1 Open terminal and type sudo gedit .bashrc

Step-2 It will ask you your password. After typing the password ,it will open the bash file. Then go to end and type below

step-3

   export JAVA_HOME="/usr/lib/jvm/java-8-openjdk-amd64/"
   export PATH=$PATH:$JAVA_HOME/bin

step-4 Then save the file and exit from file

Above is for a single user. For all users, you have to follow below steps

Step-1 gedit /etc/profile

Step-2 export JAVA_HOME="/usr/lib/jvm/java-8-openjdk-amd64/"

Step-3 export PATH=$PATH:$JAVA_HOME/bin

Hope this helps. Thanks!

In /etc/profile , if you open that will you’ll get to know that IT IS no recommended to write on that file. Instead of that make a script of your commands(suppose test.sh)go to /etc/profile.d folder and Put test.sh there. Every time you instance reboot it’ll be automatically called by /etc/profile.

I use the line:

export JAVA_HOME=$(readlink -f $(dirname $(readlink -f $(which java) ))/../)

to my ~/.profile so it uses the base of the default java directory at login time. This is for bash.

This is a very simple script to solve the problem

export JAVA_HOME_BIN=`which java`
export JAVA_HOME_DIR=`dirname $JAVA_HOME_BIN`
export JAVA_HOME=`dirname $JAVA_HOME_DIR`

And for testing:

echo $JAVA_HOME