Ubuntu - set JAVA_HOME environment variable

In this short article we would like to show how to set JAVA_HOME environment variable in Ubuntu.

Simple steps:

1. check where Java JDK is installed
   Run command:

   ls -al /usr/lib/jvm

   Output: 

   total 16
   drwxr-xr-x   3 root root 4096 sie 18 09:56 .
   drwxr-xr-x 141 root root 4096 sie 19 10:26 ..
   lrwxrwxrwx   1 root root   25 lut 20  2019 default-java -> java-1.11.0-openjdk-amd64
   lrwxrwxrwx   1 root root   21 sty 15  2020 java-1.11.0-openjdk-amd64 -> java-11-openjdk-amd64
   -rw-r--r--   1 root root 2044 lip 15 22:45 .java-1.11.0-openjdk-amd64.jinfo
   drwxr-xr-x   7 root root 4096 sie 18 09:56 java-11-openjdk-amd64

   so, Java JDK path is: /usr/lib/jvm/default-java
    
2. add JAVA_HOME to /etc/environment
   Run command:

   sudo nano /etc/environment

   Add following line over PATH:

   JAVA_HOME="/usr/lib/jvm/default-java"

   Update PATH line adding :$JAVA_HOME/bin at the end:

   PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:$JAVA_HOME/bin"

   Press ctrl+o and ctrl+x to save file and exit program.
   Screenshot:

   

3. request to reload environment variables (optional operation)
   Run command:

   source /etc/environment

   Note: it will reload currently used terminal variables only! So, run it for different terminals if it is necessary, re-login users or restart Linux.

    
4. verify JAVA_HOME configuration
   Run command:

   echo $JAVA_HOME

   Output:

   /usr/lib/jvm/default-java