Make JAVA HOME easily changable in Ubuntu

Question

In Ubuntu  I d like to switch my JAVA HOME environment variable back and forth between Java 5 and 6   I open a terminal and type in the following to set the JAVA HOME environment variable   export JAVA HOME  usr lib jvm java-1 5 0-sun   And in that same terminal window  I type the following to check that the environment variable has been updated   echo  JAVA HOME   And I see  usr lib jvm java-1 5 0-sun which is what I m expecting to see   In addition  I modify    profile and set the JAVA HOME environment variable to  usr lib jvm java-1 5 0-sun   And now for the problem--when I open a new terminal window and I check my JAVA HOME environment variable by typing in echo  JAVA HOME I see that my JAVA HOME environment variable has been reverted back to Java 6   When I reboot my machine  or log out and back in  I suppose  the JAVA HOME environment variable is set to Java 5  presumably because of the modification I made in my    profile    Is there a way around this so that I can change my JAVA HOME environment without having to log out and back in  AND make that environment variable change stick in all new terminal windows

User · Answer

Take a look at bash 1   you need a login shell to pickup the    profile  i e  the -l option

User · Answer

You need to put variable definition in the    bashrc file   From bash man page      When  an  interactive  shell that is   not a login shell is started  bash   reads and executes commands from     etc bash bashrc  and     bashrc   if   these  files  exist

User · Answer

This will probably solve your problem  https   help ubuntu com community EnvironmentVariables     Session-wide environment variables        In order to set environment variables in a way that affects a particular user s environment  one should not place commands to set their values in particular shell script files in the user s home directory  but use          pam environment - This file is specifically meant for setting a user s environment  It is not a script file  but rather consists of assignment expressions  one per line       Not recommended          profile - This is probably the best file for placing environment variable assignments in  since it gets executed automatically by the DisplayManager during the startup process desktop session as well as by the login shell when one logs-in from the textual console

User · Answer

Put the environment variables into the global  etc environment file       export JAVA HOME  usr lib jvm java-1 5 0-sun       Execute  source  etc environment  in every shell where you want the variables to be updated     source  etc environment   Check that it works     echo  JAVA HOME    usr lib jvm java-1 5 0-sun   Great  no logout needed   If you want to set JAVA HOME environment variable in only the terminal  set it in    bashrc file

User · Answer

Traditionally  if you only want to change the variable in your terminal windows  set it in  bashrc file  which is sourced each time a new terminal is opened   profile file is not sourced each time you open a new terminal   See the difference between  profile and  bashrc in question  What s the difference between  bashrc   bash profile  and  environment    bashrc should solve your problem  However  it is not the proper solution since you are using Ubuntu  See the relevant Ubuntu help page  Session-wide environment variables   Thus  no wonder that  profile does not work for you  I use Ubuntu 12 04 and xfce  I set up my  profile and it is simply not taking effect even if I log out and in  Similar experience here  So you may have to use  pam environment file and totally forget about  profile  and  bashrc  And NOTE that  pam environment is not a script file

User · Answer

Try these steps   --We are going to edit  etc profile     The environment variables are to be input at the bottom of the file  Since Ubuntu does not    give access to root folder  we will have to use a few commands in the terminal  Step1  Start Terminal  Type in command  gksudo gedit  etc profile  Step2  The profile text file will open  Enter the environment variables at the bottom of the page            Eg   export JAVA HOME  home alex jdk1 6 0 22 bin java  export PATH  home alex jdk1 6 0 22 bin  PATH   step3  save and close the file  Check if the environment variables are set by using echo command         Eg echo  PATH

User · Answer

After making changes to  profile  you need to execute the file  in order for the changes to take effect   root masternode       profile   Once this is done  the echo command will work

User · Answer

I know this is a long cold question  but it comes up every time there is a new or recent major Java release   Now this would easily apply to 6 and 7 swapping   I have done this in the past with update-java-alternatives  http   manpages ubuntu com manpages hardy man8 update-java-alternatives 8 html

[linux] Make $JAVA_HOME easily changable in Ubuntu

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