What is the correct target for the JAVA_HOME environment variable for a Linux OpenJDK Debian-based distribution?

Question

In Windows, JAVA_HOME must point to the JDK installation folder (so that JAVA_HOME/bin contains all executables and JAVA_HOME/libs contains all default jar libraries).

If I download Sun's JDK bundle and installs it in Linux, it is the same procedure.

However, I need to use Kubuntu's default OpenJDK package. The problem is that all executables are placed in /usr/bin. But the jars are placed in /usr/share/java. Since they are not under the same JAVA_HOME folder I'm having trouble with Grails and maybe there will be trouble with other applications that expect the standard Java structure.

If I use:
```
JAVA_HOME=/usr
```
All applications and scripts that want to use any Java executable can use the standard procedure call $JAVA_HOME/bin/executable. However, since the jars are in a different place, they are not always found (example: in grails I'm getting ClassDefNotFound for native2ascii).
On the other hand, if I use:
```
JAVA_HOME=/usr/share/java
```
None of the Java executables (java, javac, etc.) can be found.

So, what is the correct way of handling the JAVA_HOME variable in a Debian-based Linux?

Thanks for your help, Luis

score 103 · Accepted Answer · edited Jul 14 '15 at 11:50

103

What finally worked for me (Grails now works smoothly) is doing almost like Steve B. has pointed out:

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

This way if the user changes the default JDK for the system, JAVA_HOME still works.

default-java is a symlink to the current JVM.

edited Jul 14 '15 at 11:50

MasterAM

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answered Mar 19 '09 at 19:39

Luis Soeiro

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It seems there is no such link on Debian 7 – a1an Jan 09 '14 at 13:40
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On RHEL5.10, it is /usr/lib/jvm/java – Engineer2021 Apr 25 '14 at 16:53
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I used /usr/lib/jvm/java-7-openjdk-amd64 – Randall Bohn Aug 06 '14 at 15:02
For Oracle Linux 7 (this _should_ apply to CentOS and RHEL), I created a file called /etc/profile.d/java.sh and populated it with the following: JAVA_HOME=/usr/lib/jvm/jre-openjdk export JAVA_HOME after re-sourcing /etc/profile (by running source /etc/profile) JAVA_HOME was populated as expected. – darnold0714 Mar 04 '20 at 14:12

bbaassssiiee · Answer 2 · 2019-07-20T19:26:19.023

87

If you use alternatives to manage multiple java versions, you can set the JAVA_HOME based on the symlinked java (or javac) like this:

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

edited Jul 20 '19 at 19:26

answered Jul 18 '12 at 13:50

bbaassssiiee

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This works for me: JAVA_HOME=$(readlink -f /usr/bin/java | sed "s:/jre/bin/java::") – dpnsan Jul 25 '13 at 18:54
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Brilliant solution, solves my years long headaches with JAVA_HOME, which tends to point to different places on different operating systems. – Datageek Mar 07 '14 at 19:30
3

note that this clever solution won't work on distros like Gentoo that have `/usr/bin/java` pointing to a script (`/usr/libexec/eselect-java/run-java-tool.bash`). still, it's a nice approach. the only thing i'd change is use Bash's builtin substitution to avoid spawning `sed`, e.g.: `JAVA_HOME=$( j=$( readlink -f /usr/bin/java ) ; echo ${j%%/bin/java} )` – RubyTuesdayDONO Mar 29 '14 at 02:20
This works well :) Might want to change `javac` to `java` because not everyone has the JDK installed; only the JRE – Hanxue Apr 11 '14 at 05:08
1

@AlexisWilke now java instead of javac – bbaassssiiee May 07 '16 at 08:25
my symlink /use/bin/java points to jre/bin/java, this causes an error during compilation as I need it to point to Java jdk home. – user2441441 Apr 03 '17 at 21:27

score 7 · Answer 3 · edited Jul 14 '15 at 12:32

7

The standard Ubuntu install seems to put the various Java versions in /usr/lib/jvm. The javac, java you find in your path will softlink to this.

There's no issue with installing your own Java version anywhere you like, as long as you set the JAVA_HOME environment variable and make sure to have the new Java bin on your path.

A simple way to do this is to have the Java home exist as a softlink, so that if you want to upgrade or switch versions you only have to change the directory that this points to - e.g.:

/usr/bin/java --> /opt/jdk/bin/java,

/opt/jdk --> /opt/jdk1.6.011

edited Jul 14 '15 at 12:32

BuZZ-dEE

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answered Mar 19 '09 at 19:32

Steve B.

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it is dangerous to recommend Ubuntu solutions with Debian. They can and do vary. – RichieHH Aug 05 '10 at 00:57
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Note the requestor said he used Kubuntu, so Ubuntu solutions should be fine. – Joseph Holsten May 25 '11 at 23:30

score 1 · Answer 4 · answered Sep 02 '21 at 21:14

1

I modified one of the solution above and this seems to work no matter where java is installed, as long it's in your PATH.

JAVA_HOME=$( j=$( readlink -f $(which java) ) ; echo ${j%%/bin/java} )

answered Sep 02 '21 at 21:14

JavaAllDay

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See https://www.baeldung.com/find-java-home for options. – Leponzo Dec 31 '21 at 12:00

score 0 · Answer 5 · answered Jun 12 '12 at 06:50

0

Updated answer that will solve your problem and also just a general good how-to for installing Oracle Java 7 on Ubuntu can be found here: http://www.wikihow.com/Install-Oracle-Java-on-Ubuntu-Linux

answered Jun 12 '12 at 06:50

Jack

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Saturn Junction · Answer 6 · 2013-01-16T18:54:45.777

I've discovered similar problems with the openjdk-6-jre and openjdk-6-jre-headless packages in Ubuntu.

My problem was solved by purging the openjdk-6-jre and openjdk-6-jre-headless packages and re-installing. The alternatives are only updated on a fresh install of the openjdk-6-jre and openjdk-6-jre-headless packages.

Below is a sample of installing after purging:

aptitude purge openjdk-6-jre openjdk-6-jre-headless # to ensure no configuration exists
aptitude install --without-recommends openjdk-6-jre # Installing without some extras
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reading extended state information
Initializing package states... Done
The following NEW packages will be installed:
  ca-certificates-java{a} java-common{a} libavahi-client3{a} libavahi-common-data{a} libavahi-common3{a} libcups2{a} libflac8{a} libgif4{a} libnspr4-0d{a} libnss3-1d{a} libogg0{a} libpulse0{a} libsndfile1{a} libvorbis0a{a} libvorbisenc2{a} libxi6{a} libxtst6{a}
  openjdk-6-jre openjdk-6-jre-headless{a} openjdk-6-jre-lib{a} tzdata-java{a}
The following packages are RECOMMENDED but will NOT be installed:
  icedtea-6-jre-cacao icedtea-netx ttf-dejavu-extra
0 packages upgraded, 21 newly installed, 0 to remove and 119 not upgraded.
Need to get 0B/34.5MB of archives. After unpacking 97.6MB will be used.
Do you want to continue? [Y/n/?]
Writing extended state information... Done
Selecting previously deselected package openjdk-6-jre-lib.
(Reading database ... 62267 files and directories currently installed.)
Unpacking openjdk-6-jre-lib (from .../openjdk-6-jre-lib_6b24-1.11.5-0ubuntu1~10.04.2_all.deb) ...
...
Processing triggers for man-db ...
Setting up tzdata-java (2012e-0ubuntu0.10.04) ...
...
Setting up openjdk-6-jre-headless (6b24-1.11.5-0ubuntu1~10.04.2) ...
update-alternatives: using /usr/lib/jvm/java-6-openjdk/jre/bin/java to provide /usr/bin/java (java) in auto mode.
update-alternatives: using /usr/lib/jvm/java-6-openjdk/jre/bin/keytool to provide /usr/bin/keytool (keytool) in auto mode.
update-alternatives: using /usr/lib/jvm/java-6-openjdk/jre/bin/pack200 to provide /usr/bin/pack200 (pack200) in auto mode.
update-alternatives: using /usr/lib/jvm/java-6-openjdk/jre/bin/rmid to provide /usr/bin/rmid (rmid) in auto mode.
update-alternatives: using /usr/lib/jvm/java-6-openjdk/jre/bin/rmiregistry to provide /usr/bin/rmiregistry (rmiregistry) in auto mode.
update-alternatives: using /usr/lib/jvm/java-6-openjdk/jre/bin/unpack200 to provide /usr/bin/unpack200 (unpack200) in auto mode.
update-alternatives: using /usr/lib/jvm/java-6-openjdk/jre/bin/orbd to provide /usr/bin/orbd (orbd) in auto mode.
update-alternatives: using /usr/lib/jvm/java-6-openjdk/jre/bin/servertool to provide /usr/bin/servertool (servertool) in auto mode.
update-alternatives: using /usr/lib/jvm/java-6-openjdk/jre/bin/tnameserv to provide /usr/bin/tnameserv (tnameserv) in auto mode.
update-alternatives: using /usr/lib/jvm/java-6-openjdk/jre/lib/jexec to provide /usr/bin/jexec (jexec) in auto mode.
Setting up openjdk-6-jre (6b24-1.11.5-0ubuntu1~10.04.2) ...
update-alternatives: using /usr/lib/jvm/java-6-openjdk/jre/bin/policytool to provide /usr/bin/policytool (policytool) in auto mode.
...

You can see above that update-alternatives is run to set up links for the various Java binaries.

After this install, there are also links in /usr/bin, links in /etc/alternatives, and files for each binary in /var/lib/dpkg/alternatives.

ls -l /usr/bin/java /etc/alternatives/java /var/lib/dpkg/alternatives/java
lrwxrwxrwx 1 root root  40 2013-01-16 14:44 /etc/alternatives/java -> /usr/lib/jvm/java-6-openjdk/jre/bin/java
lrwxrwxrwx 1 root root  22 2013-01-16 14:44 /usr/bin/java -> /etc/alternatives/java
-rw-r--r-- 1 root root 158 2013-01-16 14:44 /var/lib/dpkg/alternatives/java

Let's contast this with installing without purging.

aptitude remove openjdk-6-jre
aptitude install --without-recommends openjdk-6-jre
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reading extended state information
Initializing package states... Done
The following NEW packages will be installed:
  ca-certificates-java{a} java-common{a} libavahi-client3{a} libavahi-common-data{a} libavahi-common3{a} libcups2{a} libflac8{a} libgif4{a} libnspr4-0d{a} libnss3-1d{a} libogg0{a} libpulse0{a} libsndfile1{a} libvorbis0a{a} libvorbisenc2{a} libxi6{a} libxtst6{a}
  openjdk-6-jre openjdk-6-jre-headless{a} openjdk-6-jre-lib{a} tzdata-java{a}
The following packages are RECOMMENDED but will NOT be installed:
  icedtea-6-jre-cacao icedtea-netx ttf-dejavu-extra
0 packages upgraded, 21 newly installed, 0 to remove and 119 not upgraded.
Need to get 0B/34.5MB of archives. After unpacking 97.6MB will be used.
Do you want to continue? [Y/n/?]
Writing extended state information... Done
Selecting previously deselected package openjdk-6-jre-lib.
(Reading database ... 62293 files and directories currently installed.)
Unpacking openjdk-6-jre-lib (from .../openjdk-6-jre-lib_6b24-1.11.5-0ubuntu1~10.04.2_all.deb) ...
...
Processing triggers for man-db ...
...
Setting up openjdk-6-jre-headless (6b24-1.11.5-0ubuntu1~10.04.2) ...

Setting up openjdk-6-jre (6b24-1.11.5-0ubuntu1~10.04.2) ...
...

As you see, update-alternatives is not triggered.

After this install, there are no files for the Java binaries in /var/lib/dpkg/alternatives, no links in /etc/alternatives, and no links in /usr/bin.

The removal of the files in /var/lib/dpkg/alternatives also breaks update-java-alternatives.

score 0 · Answer 7 · answered Mar 06 '13 at 23:51

0

Ubuntu 12.04 this works...

JAVA_HOME=/usr/lib/jvm/java-6-openjdk-i386/jre

answered Mar 06 '13 at 23:51

Alex

1

Greg Henry · Answer 8 · 2015-09-06T21:16:22.117

0

As an update for fedora user , alternatives set current java directory to /usr/java/default

so you have to set your JAVA_HOME to /usr/java/default to always have alternatives curent selection in your classpath

HTH !

edited Sep 06 '15 at 21:16

answered Sep 06 '15 at 21:05

Greg Henry

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score 0 · Answer 9 · answered Mar 14 '11 at 15:53

If you have issues with JAR files not being found I would also ensure your CLASSPATH is set to include the location of those files. I do find however that the CLASSPATH often needs to be set differently for different programs and often ends up being something to set uniquely for individual programs.

score 0 · Answer 10 · edited Nov 21 '19 at 11:25

0

I always tend to set the JAVA_HOME according to the /usr/bin/java.

JAVA_HOME="$(dirname -- "$(dirname -- "$(readlink -f /usr/bin/java)")")"

This way, both alternatives point to the same location

edited Nov 21 '19 at 11:25

David Buck

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answered Nov 21 '19 at 10:23

Ivo

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score 0 · Answer 11 · answered Mar 19 '09 at 19:28

0

I usually don't have any JAVA_HOME environment variable. Java can set it up itself. Inside java java.home system property should be available.

answered Mar 19 '09 at 19:28

iny

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I usually don't have it either. However, if I don't set it up, grails complains that JAVA_HOME is not there and aborts. – Luis Soeiro Mar 19 '09 at 19:32
1

ant needs it too in debian which is the context – RichieHH Aug 05 '10 at 00:55

score 0 · Answer 12 · answered Mar 19 '09 at 20:01

0

Try setting the JAVA_LIB variable also.

answered Mar 19 '09 at 20:01

Cantillon

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elcuco · Answer 13 · 2010-08-11T05:02:57.260

-1

Please see what the update-alternatives command does (it has a nice man...).

Shortly - what happens when you have java-sun-1.4 and java-opensouce-1.0 ... which one takes "java"? It debian "/usr/bin/java" is symbolic link and "/usr/bin/java-sun-1.4" is an alternative to "/usr/bin/java"

Edit: As Richard said, update-alternatives is not enough. You actually need to use update-java-alternatives. More info at:

https://help.ubuntu.com/community/Java

edited Aug 11 '10 at 05:02

answered Mar 19 '09 at 19:47

elcuco

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update-alternatives is not enough. It needs to be update-java-alternatives – RichieHH Aug 05 '10 at 00:56
@Richard: yes, noted. First time I head about it so I googled, and found Ubuntu's documentation. Thanks! – elcuco Aug 11 '10 at 05:03

score -1 · Answer 14 · answered Mar 20 '09 at 10:51

-1

As far as I remember, I used the update-java-alternatives script instead of the update-alternatives. And it did set the JAVA_HOME for me correctly.

answered Mar 20 '09 at 10:51

Tobias Schulte

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It doesn't in Ubuntu 20.4 – Martin Schröder Nov 09 '20 at 17:51

score -2 · Answer 15 · answered Mar 19 '09 at 19:26

My correct target has always been to download it from Sun and just install it that way. Then you know exactly what directory everything goes in.

But if you'd prefer to stick with the odd way that Debian installs it, my best guess would be the parent directory just above where the java and javac binaries are located.

(since when you specify it in your path it's $JAVA_HOME/bin) (So in your case it would be ... $JAVA_HOME/share and $JAVA_HOME would be /usr ?)

Eh, that doesn't sound right...

I'm interested to hear the answer to this too!

When using debian you really need to keep with the debian structures or later system updates will leave you with a broken system. — RichieHH, Aug 05 '10 at 00:56

What is the correct target for the JAVA_HOME environment variable for a Linux OpenJDK Debian-based distribution?

15 Answers15

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