Linux / Ubuntu - set system JAVA_HOME env variable

In this short article we woukld like to show how to set JAVA_HOME environment variable in Ubutnu 18.04.

Quick solution (create /etc/profile.d/jdk file with following content):

export JAVA_HOME="/usr/lib/jvm/java-14-oracle"
export PATH=$PATH:$JAVA_HOME/bin

Where: /usr/lib/jvm/java-14-oracle should be changed to Java instalation directory path.

Detailed description

The approach presented in article should be working on Debian or latest Ubuntu too.

Hint: for java installed from package name ended with *.-set-default postfix, JAVA_HOME should be set automatically, e.g.

sudo apt-get install oracle-java14-set-default

Simple steps:

1. find java directory path:

ls -al /usr/lib/jvm/

Output:

total 32
drwxr-xr-x   5 root root 4096 paź  9 14:25 .
drwxr-xr-x 143 root root 4096 paź  9 14:25 ..
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
drwxr-xr-x   9 root root 4096 paź  9 14:24 java-14-oracle
-rw-r--r--   1 root root 3559 paź  9 14:24 .java-14-oracle.jinfo
lrwxrwxrwx   1 root root   20 sie  3 03:16 java-1.8.0-openjdk-amd64 -> java-8-openjdk-amd64
-rw-r--r--   1 root root 2712 sie  3 03:16 .java-1.8.0-openjdk-amd64.jinfo
drwxr-xr-x   7 root root 4096 sie 19 12:26 java-8-openjdk-amd64

Note: we want to use: /usr/lib/jvm/java-14-oracle (it is line 8).

2. add /etc/profile.d/jdk file with following content:

export JAVA_HOME="/usr/lib/jvm/java-14-oracle"
export PATH=$PATH:$JAVA_HOME/bin

Note: you can add it on the beginning of /etc/profile too - this approach is not recommended because of messing in scripts politics.

3. rebot operating system with:

sudo reboot

4. test JAVA_HOME variable with:

echo $JAVA_HOME

Output:

/usr/lib/jvm/java-14-oracle