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

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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

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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 - gt   usr lib jvm java-6-openjdk jre bin java lrwxrwxrwx 1 root root  22 2013-01-16 14 44  usr bin java - gt   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

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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

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Try setting the JAVA LIB variable also

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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

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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

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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 -- gt   opt jdk bin java    opt jdk -- gt   opt jdk1 6 011

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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

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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

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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

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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

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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

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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

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Ubuntu 12 04 this works     JAVA HOME  usr lib jvm java-6-openjdk-i386 jre

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

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