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What is the correct target for the JAVA_HOME environment variable for a Linux OpenJDK Debian-based distribution?
Asked Answered
Solved javagrailsjava-homedebian-based
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15

97

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.

  1. 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).

  2. 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

Background answered 19/3, 2009 at 19:23 Comment(0)
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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.

Background answered 19/3, 2009 at 19:39 Comment(4)
It seems there is no such link on Debian 7 – Ardene
On RHEL5.10, it is /usr/lib/jvm/java – Dews
I used /usr/lib/jvm/java-7-openjdk-amd64 – Athirst
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. – Preordain
S
89

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=$(readlink -f /usr/bin/java | sed "s:bin/java::")
Seaworthy answered 18/7, 2012 at 13:50 Comment(6)
This works for me: JAVA_HOME=$(readlink -f /usr/bin/java | sed "s:/jre/bin/java::") – Bronchoscope
Brilliant solution, solves my years long headaches with JAVA_HOME, which tends to point to different places on different operating systems. – Youngster
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} ) – Detwiler
This works well :) Might want to change javac to java because not everyone has the JDK installed; only the JRE – Skateboard
@AlexisWilke now java instead of javac – Seaworthy
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. – Correspondent
F
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
Foreskin answered 19/3, 2009 at 19:32 Comment(2)
it is dangerous to recommend Ubuntu solutions with Debian. They can and do vary. – Durable
Note the requestor said he used Kubuntu, so Ubuntu solutions should be fine. – Deettadeeyn
Y
2

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} )
Yearning answered 2/9, 2021 at 21:14 Comment(1)
See baeldung.com/find-java-home for options. – Ribera
I
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.

Incrocci answered 19/3, 2009 at 19:28 Comment(2)
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. – Background
ant needs it too in debian which is the context – Durable
C
0

Try setting the JAVA_LIB variable also.

Cambrian answered 19/3, 2009 at 20:1 Comment(0)
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0

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.

Minda answered 14/3, 2011 at 15:53 Comment(0)
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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

Fears answered 12/6, 2012 at 6:50 Comment(0)
A
0

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.

Alper answered 16/1, 2013 at 18:48 Comment(0)
D
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 !

Deniable answered 6/9, 2015 at 21:5 Comment(0)
Z
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

Zealot answered 21/11, 2019 at 10:23 Comment(0)
A
-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

Acidic answered 19/3, 2009 at 19:47 Comment(2)
update-alternatives is not enough. It needs to be update-java-alternatives – Durable
@Richard: yes, noted. First time I head about it so I googled, and found Ubuntu's documentation. Thanks! – Acidic
P
-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.

Propagation answered 20/3, 2009 at 10:51 Comment(1)
It doesn't in Ubuntu 20.4 – Interstratify
L
-1

Ubuntu 12.04 this works...

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

Lection answered 6/3, 2013 at 23:51 Comment(0)
P
-2

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!

Pithos answered 19/3, 2009 at 19:26 Comment(1)
When using debian you really need to keep with the debian structures or later system updates will leave you with a broken system. – Durable

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