如何在 WSL2 上从 ubuntu shell 设置 JAVA_HOME？

Question

I installed WSL2 on my Windows 10 Home. I want to use Maven (which I verified is installed correctly on Windows).

In an ubuntu shell from Windows Terminal, I set JAVA_HOME in my .profile but it would not get set. I ran these commands to try out the correct way to set JAVA_HOME but they do not work.

user@DESKTOP:/mnt/c/Users/user$ mvn
The JAVA_HOME environment variable is not defined correctly
This environment variable is needed to run this program
NB: JAVA_HOME should point to a JDK not a JRE

user@DESKTOP:/mnt/c/Users/user$ JAVA_HOME=/mnt/c/Program\ Files/Java/jdk-11.0.10/bin
user@DESKTOP:/mnt/c/Users/user$ cd $JAVA_HOME
-bash: cd: too many arguments

user@DESKTOP:/mnt/c/Users/user$ cd /mnt/c/Program\ Files/Java/jdk-11.0.10/bin
user@DESKTOP:/mnt/c/Program Files/Java/jdk-11.0.10/bin$ mvn --version
The JAVA_HOME environment variable is not defined correctly
This environment variable is needed to run this program
NB: JAVA_HOME should point to a JDK not a JRE

user@DESKTOP:/mnt/c/Program Files/Java/jdk-11.0.10/bin$ JAVA_HOME=/mnt/c/'Program\ Files'/Java/jdk-11.0.10/bin
user@DESKTOP:/mnt/c/Program Files/Java/jdk-11.0.10/bin$ cd $JAVA_HOME
-bash: cd: too many arguments

user@DESKTOP:/mnt/c/Program Files/Java/jdk-11.0.10/bin$ JAVA_HOME=/mnt/c/'Program\ Files'/Java/jdk-11.0.10
user@DESKTOP:/mnt/c/Program Files/Java/jdk-11.0.10/bin$ cd $JAVA_HOME
-bash: cd: too many arguments

user@DESKTOP:/mnt/c/Program Files/Java/jdk-11.0.10/bin$ cd /mnt/c/Program\ Files/Java/jdk-11.0.10/bin
user@DESKTOP:/mnt/c/Program Files/Java/jdk-11.0.10/bin$ pwd
/mnt/c/Program Files/Java/jdk-11.0.10/bin

user@DESKTOP:/mnt/c/Program Files/Java/jdk-11.0.10/bin$ echo $JAVA_HOME
/mnt/c/Program\ Files/Java/jdk-11.0.10
user@DESKTOP:/mnt/c/Program Files/Java/jdk-11.0.10/bin$


user@DESKTOP:/mnt/c/Program Files/Java/jdk-11.0.10/bin$ export JAVA_HOME="/mnt/c/Program Files/Java/jdk-11.0.10"
user@DESKTOP:/mnt/c/Program Files/Java/jdk-11.0.10/bin$ cd $JAVA_HOME
-bash: cd: too many arguments

user@DESKTOP:~$ export JAVA_HOME="/mnt/c/Program\ Files/Java/jdk-11.0.10"
user@DESKTOP:~$ cd $JAVA_HOME
-bash: cd: too many arguments

UPDATE:

I followed user Aran's (unfortunately deleted) answer below - I edited /etc/environment and added

export JAVA_HOME="/mnt/c/Program Files/Java/jdk-11.0.10"

then in .bashrc I added

source /etc/environment

and thought it worked because when I did an env in the ubuntu shell, I saw JAVA_HOME

I installed mvn and it still gives the same error:

$ mvn The JAVA_HOME environment variable is not defined correctly This environment variable is needed to run this program NB: JAVA_HOME should point to a JDK not a JRE 

I think it is the space in "Program Files". I do have JDK 11 installed. Verified by navigating to JAVA_HOME/bin and I can see javac.exe.

So the issue is not fixed.

UPDATE 2

Here is what the Maven script tries to do with JAVA_HOME, which may help find the correct workaround:

if [ -z "$JAVA_HOME" ] ; then
  JAVACMD=`which java`
else
  JAVACMD="$JAVA_HOME/bin/java"
fi

if [ ! -x "$JAVACMD" ] ; then
  echo "The JAVA_HOME environment variable is not defined correctly" >&2
  echo "This environment variable is needed to run this program" >&2
  echo "NB: JAVA_HOME should point to a JDK not a JRE" >&2
  exit 1
fi

Please note that the script goes through the "else" part, and that the ". -x" part is where it fails.

---

Note : This is not a duplicate of this question . I do not have access to how Maven is accessing JAVA_HOME. The question is not about cd $JAVA_HOME . It is about using mvn Maven. If Maven is using $JAVA_HOME internally, there is no way I can see how to make it use "$JAVA_HOME"

Answer 1

Workaround: (not an exact solution to the question)

Set the JAVA_HOME variable from Windows, via the gui and use Windows Powershell instead of ubuntu shell.

Answer 2

Add copy of java.exe with the name just "java". That will prevent mvn from complaining - it looks for "$JAVACMD"which is defined as JAVACMD="$JAVA_HOME/bin/java"

Answer 3

I solved it by installing OpenJDK 17 on WSL(link below).

Run the following commands in WSL (I was using Windows Terminal)

1. sudo apt update
2. sudo apt install openjdk-17-jdk
3. java --version

Link: https://techviewleo.com/install-java-openjdk-on-ubuntu-linux/