问题
I am new to Linux system and there seem to be too many Java folders.
java -version gives me:
- java version \"1.7.0_55\"
- OpenJDK Runtime Environment (rhel-2.4.7.1.el6_5-x86_64 u55-b13)
- OpenJDK 64-Bit Server VM (build 24.51-b03, mixed mode)
When I am trying to build a Maven project , I am getting error:
Error: JAVA_HOME is not defined correctly.
We cannot execute /usr/java/jdk1.7.0_05/bin/java
Could you please tell me which files I need to modify for root as well as not-root user and where exactly is java located?
回答1:
find /usr/lib/jvm/java-1.x.x-openjdkvim /etc/profilePrepend sudo if logged in as not-privileged user, ie.
sudo vim- Press 'i' to get in insert mode
add:
export JAVA_HOME="path that you found" export PATH=$JAVA_HOME/bin:$PATH- logout and login again, reboot, or use
source /etc/profileto apply changes immediately in your current shell
回答2:
For all users, I would recommend placing the following line in /etc/profile
export JAVA_HOME=$(readlink -f /usr/bin/javac | sed "s:/bin/javac::")
This will update dynamically and works well with the alternatives system. Do note though that the update will only take place in a new login shell.
回答3:
You could use /etc/profile or better a file like /etc/profile.d/jdk_home.sh
export JAVA_HOME=/usr/java/jdk1.7.0_05/
You have to remember that this file is only loaded with new login shells.. So after bash -l or a new gnome-session and that it doesn't change with new Java versions.
回答4:
None of the other answers were "sticking" for me in RHEL 7, even setting JAVA_HOME and PATH directly in /etc/profile or ~/.bash_profile would not work. Each time I tried to check if JAVA_HOME was set, it would come up blank:
$ echo $JAVA_HOME
(<-- no output)
What I had to do was set up a script in /etc/profile.d/jdk_home.sh:
#!/bin/sh
export JAVA_HOME=/opt/ibm/java-x86_64-60/
export PATH=$JAVA_HOME/bin:$PATH
I initially neglected the first line (the #!/bin/sh), and it won't work without it.
Now it's working:
$ echo $JAVA_HOME
/opt/ibm/java-x86_64-60/
回答5:
It's Very easy to set path in Linux . Do as follows :
Step-1 Open terminal and type sudo gedit .bashrc
Step-2 It will ask you your password . After typing password ,it will open the bash file . Then go to end and type below
step-3
export JAVA_HOME="/usr/lib/jvm/java-8-openjdk-amd64/"
export PATH=$PATH:$JAVA_HOME/bin
step-4 Then save the file and exit from file
Above is for a single user. For all users, you have to follow below steps
Step-1 gedit /etc/profile
Step-2 export JAVA_HOME="/usr/lib/jvm/java-8-openjdk-amd64/"
Step-3 export PATH=$PATH:$JAVA_HOME/bin
Hope this helps. Thanks!
回答6:
Doing what Oracle does (as a former Sun Employee I can't get used to that one)
ln -s latestJavaRelease /usr/java/default
Where latestJavaRelease is the version that you want to use
then export JAVA_HOME=/usr/java/default
回答7:
The answer is given previous posts is valid. But not one answer is complete with respect to:
- Changing the /etc/profile is not recommended simply because of the reason (as stated in /etc/profile):
- It's NOT a good idea to change this file unless you know what you are doing. It's much better to create a custom.sh shell script in /etc/profile.d/ to make custom changes to your environment, as this will prevent the need for merging in future updates.*
So as stated above create /etc/profile.d/custom.sh file for custom changes.
Now, to always keep updated with newer versions of Java being installed, never put the absolute path, instead use:
#if making jdk as java home
export JAVA_HOME=$(readlink -f /usr/bin/javac | sed "s:/bin/javac::")
OR
#if making jre as java home
export JAVA_HOME=$(readlink -f /usr/bin/java | sed "s:/bin/java::")
- And remember to have #! /bin/bash on the custom.sh file
回答8:
Copy the bin file path you installed
YOUR PATH
open terminal and edit environment file by typing following command,
sudo nano /etc/environment
In this file, add the following line (replacing YOUR_PATH by the just copied path):
JAVA_HOME="YOUR_PATH"
That should be enough to set the environment variable. Now reload this file:
source /etc/environment
now test it by executing:
echo $JAVA_HOME
回答9:
On Linux I add this line to my ~/.profile:
export JAVA_HOME=$(readlink -ze /usr/bin/javac | xargs -0 dirname -z | xargs -0 dirname)
回答10:
Step 1 - check the current java version by "echo $JAVA_HOME"
Step 2 - vim /etc/profile
Step 3 - At the end of file you will find export JAVA_HOME, we need to provide the new path here, make sure that it is not relative.
Step 4 - Save and exit :wq
Step 5 - "source /etc/profile/", this would execute the change
Step 6 - Again do a echo $JAVA_HOME - change would have been reflected.
回答11:
Probably a good idea to source whatever profile you edit to save having to use a fresh login.
either: source /etc/ or . /etc/
Where is whatever profile you edited.
回答12:
While we are up to setting JAVA_HOME, let me share some benefits of setting JAVA_HOME or any other environment variable:
1) It's easy to upgrade JDK without affecting your application startup and config file which points to JAVA_HOME. you just need to download new version and make sure your JAVA_HOME points to new version of Java. This is best benefit of using environment variable or links.
2) JAVA_HOME variable is short and concise instead of full path to JDK installation directory.
3) JAVA_HOME variable is platform independence i.e. if your startup script uses JAVA_HOME then it can run on Windows and UNIX without any modification, you just need to set JAVA_HOME on respective operating system.
Read more: http://javarevisited.blogspot.com/2012/02/how-to-set-javahome-environment-in.html#ixzz4BWmaYIjH
回答13:
This is a very simple script to solve the problem
export JAVA_HOME_BIN=`which java`
export JAVA_HOME_DIR=`dirname $JAVA_HOME_BIN`
export JAVA_HOME=`dirname $JAVA_HOME_DIR`
And for testing:
echo $JAVA_HOME
回答14:
Posting as answer, as I don't have the privilege to comment.
Point to note: follow the accepted answer posted by "That Dave Guy".
After setting the variables, make sure you set the appropriate permissions to the java directory where it's installed.
chmod -R 755 /usr/java
回答15:
Just add this command to your dockerfile
RUN echo "JAVA_HOME=$(readlink -f /usr/bin/java | sed "s:bin/java::")" | tee -a /etc/profile && source /etc/profile && echo $JAVA_HOME
回答16:
1...Using the short cut Ctlr + Alt + T to open terminal
2...Execute the below command:
echo export JAVA_HOME='$(readlink -f /usr/bin/javac | sed "s:/bin/javac::")' | sudo tee /etc/profile.d/jdk_home.sh > /dev/null
3...(Recommended) Restart your VM / computer. You can use source /etc/source if don't want to restart computer
4...Using the short cut Ctlr + Alt + T to open terminal
5...Verified JAVA_HOME installment with
echo $JAVA_HOME
One-liner copy from flob, credit to them
回答17:
I use the line:
export JAVA_HOME=$(readlink -f $(dirname $(readlink -f $(which java) ))/../)
to my ~/.profile so it uses the base of the default java directory at login time. This is for bash.
来源：https://stackoverflow.com/questions/24641536/how-to-set-java-home-in-linux-for-all-users