How to Use the Command Update-Alternatives --Config Java

OpenJDK and update-alternatives command

While this can be a problem for many software, this is a specific problem for Java on Ubuntu. Fortunately there is a specific solution, a program, call:

update-java-alternatives

I have just use it the following way:

sudo update-java-alternatives -s java-1.14.0-openjdk-amd64

It have change the alternatives of most of the Java related tools.

More comment on this subject can be found on askubuntu for a similar question. This question is also related, and an answer link to the same program.

Have bash script answer interactive prompts

This is not "auto-completion", this is automation. One common tool for these things is called Expect.

You might also get away with just piping input from yes.

alternatives --config java bash script

Generally, you can feed any program that expects something on the standard input like this:

echo -e "line 1\nline 2\nline 3" | program

update-alternatives: warning: /etc/alternatives/java is dangling

Assuming you installed the OpenJDK6 with:

sudo apt-get install openjdk-6-jdk

In Ubuntu 64 bit, make sure the paths are valid for your installation (change if using 32bit version):

/usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java

/usr/lib/jvm/java-6-openjdk-amd64/bin/javac

Setup update-alternatives:

sudo update-alternatives --install "/usr/bin/java" "java" "/usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java" 1
sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/lib/jvm/java-6-openjdk-amd64/bin/javac" 1

sudo update-alternatives --set java /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java
sudo update-alternatives --set javac /usr/lib/jvm/java-6-openjdk-amd64/bin/javac

Alternatively, make sure the correct version is checked for both Java and compiler:

sudo update-alternatives --config java
sudo update-alternatives --config javac

List the installed Java alternatives with:

sudo update-alternatives --list java
sudo update-alternatives --list javac

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