Everywhere I search, it says you can get an environment variable by using System.getenv(str).
It's not working for me. Here's what I am doing:
OS : Mac OS x 10.7
Java 1.6.x
If I do export abc=/hello/ in my terminal and then echo $abc, it gives me the variable. If I close the terminal, reopen it again and do echo $abc, it's gone. To overcome this, I edited my .bash_profile file and inserted export abc=/hello/. Close the terminal, do echo $abc and it works. So I understood that the env variable is permanent now.
Now if in my java console app, I print System.getenv("abc"), it returns null. What am I missing?
The reason that you needed to put the export in your .bash_profile is that setting environment variables in a shell only persist the variables in that shell, and - since you used export - to children of that shell, or in other words, other programs launched by that shell.
If you're running your java code from Eclipse, and you launch Eclipse from a shell with your environment variables set, then your program should see the added environment variables. To launch Eclipse from the shell, you'll need to use the OS X open command:
$ open /Applications/eclipse/Eclipse.app
Alternately, you can set the environment variables within your Eclipse project, and you'll need to do this if you're not launching Eclipse from a shell with the proper environment. In the Run Configurations dialog, look for a tab named Environment. Here you'll find a table for adding environment variables that will be passed to your program.
It's better to add the environment variables to the Run Configuration since that way they'll always be available to your project. Your code doesn't actually care where the environment variables are coming from, and adding them to the project is simpler, and will work the same way on different platforms.
Of course, when you run your program outside Eclipse, you'll need to make sure that the same environment variables exist in the shell where you e.g. run java.
Eclipse does not use the system's env variables unless launched directly from the shell (which is how it is generally launched, by clicking its icon). In that case you will have to explicitly set the required env variables in the environment tab of the run configuration of the program.
I too faced The same issue , I resolved it this way.
Open Terminal
cd to the folder where eclipse.app is located E.g cd /Users/Shared/eclipse/jee-2020-09
Type open Eclipse.app/
Eclipse will now open and will be able to access the system environment variables as well.
Check it using the code:
System.getenv().forEach((k, v) -> {
System.out.println("ENV : " + k + ":" + v);
});
Related
I am setting environment variable in my machine using export MY_KEY=foo. And I am trying to fetch it in JVM using System.getenv("MY_KEY"). This returns null. But running echo $MY_KEY shows foo on the terminal.
I have tried restarting the IDE. Doesn't work, still.
The environment variable is only available to sub processes of the shell that exported it. Did you start your IDE from that shell?
If you want the variable to be available all the time, you need to add it
to the /etc/profile file or create a extra file in /etc/profile.d. It depends on your operating system.
I added some exportable environment variables in my bash_profile and my profile files in the following format export "X=y". This worked as it should, now I want to remove them permanently . I've tried the following methods:
Deleting the exported variables from the bash_profile and the profile files, and saving the files, and calling source ~/.bash_profile and source ~/.profile.
Called "unset X" in terminal window. Before I could call "echo $X" which would display y, now it displays nothing.
Rebooting the Mac Computer.
Still however, whenever I call Java's System.getenv(X), env variable X's value (y) is still returned. What else do I need to do to completely eliminate an env variable from my system in MacOS Mojave?
It appears you believe environment variables are global. That is, modifying the value in one program, such as a running terminal, will affect the value in a different program. That is not how env vars work in a UNIX like OS. Each process is provided a copy of the env vars provided by the parent process. That is, they are inherited from the parent process.
The fact that you have to unset X in a terminal to remove it means that either it is being inherited by the shell from the terminal process or your shell is setting it. In the latter case the specific files read when a shell starts depends on the shell. But /etc/profile is read by most interactive shells so you might want to look there.
You say your Java app is run by Tomcat but failed to mention how Tomcat is started. That is important for the reasons I mention above.
Note that macOS uses a daemon named launchd to manage running most services. Those services are configured via "plist" files. See man launchd.plist. Those launchd config files support defining custom env vars. That is slightly unusual but worth looking at. See if any of the files in ~/Library/LaunchAgents, /Library/LaunchAgents, or /Library/LaunchDaemons mention the env var.
I am working on a ubuntu 14.0.4 machine.
I exported a variable TEST_HOME in my .bashrc file using
export TEST_HOME=/home/dev/code/test
When I tried echo $TEST_HOME from terminal, it returned /home/dev/code/test
So far, so good.
When I try from Java code :
String value = System.getenv("TEST_HOME");
value is null.
Am I missing something here?
Mentioning the variable in .bashrc will work only for programs started from shell. For system wide environment variables mention it in /etc/environment.
Refer Ubuntu Environment variables
.bashrc would set environment variable only for bash shell. To set it system wide set it in /etc/environment file.
Since you are using eclipse, and it does not run within bash shell, it is not getting the variable you are setting. If you run your programme using java command line in your terminal then it should get it.
Setting variable in /etc/environment would make it available to eclipse. You will need to restart your machine once you update /etc/environment.
I did the following steps but java does not seem to be working for me, do I need to restart my system if yes then why?
1. Right click My Computer->Advence Option->Environment Varibles->System Variables
2. variable : Path->Edit
3. Copy your jdk bin directory i.e.C:\Program Files\Java\jdk1.7.0_51\bin
4. Paste it after putting a semi-colon(;) in value section
i am getting below error while running java in cmd
C:\Users\User>java -version
Error: opening registry key 'Software\JavaSoft\Java Runtime Environment'
Error: could not find java.dll
Error: Could not find Java SE Runtime Environment.
No, but you will need to close and recreate any cmd windows, running java programs, or the like.
To check it's correct, open a new cmd window and type set -> review the information for PATH and JAVA_HOME.
You should set two things:
JAVA_HOME
PATH
The first lies under the "User variables for [your user name]" section. Add the JAVA_HOME variable and set it to where your jdk is installed. i.e. C:\Program Files\Java\jdk1.7.0_51\
The second lies under the "System variables" section. You should find the "path" variable, and edit it. Then, append ";%JAVA_HOME%\bin" (minus the quotes) to the end of the path variable.
After you have done this, save the variables and close that window clicking the "ok" button. Close down all instances of the command prompt (and any IDE you may be developing with such as Eclipse or NetBeans), and reopen one command prompt. Then, if you would like to test whether or not your changes worked and are in effect, try the following:
echo %JAVA_HOME%
This should output where you set your java home variable to.
echo %PATH%
At the end of what is output, you should see your java home\bin addition to the path variable
java -version
If you can run this command from the command line, it means that your environment was set up correctly and java is now in your path.
Not necessary. Quit and Open the command prompt again (if any) that runs the java process and type java -version to check if it installed successfully.
If you are using mac, source ~/.bashrc or source ~/.zshrc should refresh your environmental variable. No need to re-start the terminal even.
No, you don't need to restart your system.
However, you have to restart your command prompt application to update the changes done on Environment variables.
NO.
You don't need to restart the system, but just the application like cmd or any IDE you are using for java development (i.e Eclipse) need to restart.
And to confirm that the java path is set that you have mentioned in JAVA_HOME environment variable, you can open cmd and you can check with commands echo %JAVA_HOME% or echo %PATH%.
I reinstall the JDK and set the JAVA_HOME and PATH variable again. now it's working.
In my case under user variable section(for particularuser) JAVA_HOME set to jre not jdk path . I change it to JDK path , It worked for me
yes need to restart cmd prompt after env variable change
How do I set a java environment variable that can be read with System.getenv() on Mac OS X Lion? I developing in Eclipse.
I used this command in the terminal export VAR_NAME=Value but System.getEnv(VAR_NAME) returns null.
I tried java -DVAR_NAME=Value but nothing is executed. I only get the java arguments help.
I created in my current project folder the file .bash_profile with the content: export VAR_NAME=Value. It's not working.
I also created the folder .MacOSX with a single file inside environment.plist and in this file I wrote the property and its value using XCode. Nothing is working.
How do I do it?
It is not clear what you are actually doing here. If you are trying to set an environment variable for a Java command you are launching from Eclipse, then the simple solution is to set it via the Eclipse command launcher configuration. Another alternative is to:
exit Eclipse,
run export VAR_NAME=Value in a command shell instance, and
launch Eclipse from that same shell instance.
Re the things you tried.
I used this command in the terminal export VAR_NAME=Value but System.getEnv(VAR_NAME) returns null.
If you run the export command from a command prompt, and then immediately launch the command from the same command prompt, that should work. The export command is telling the shell instance used by the command prompt to add VAR_NAME to this list of environment variables it exports to child processes that started after running the export command. Child processes that have all ready been started won't see the changes.
I strongly suspect that you ran the export after you launched Eclipse ... or that you didn't start Eclipse from that shell instance. If either of those two is true, the export command wouldn't affect Eclipse's environment variables which it (by default) passes on to any Java program you launch from Eclipse.
I tried java -DVAR_NAME=Value but nothing is executed. I only get the java arguments help.
That fails for a couple of reasons:
the -DVAR_NAME=... is setting a system property not an environment variable, and
you haven't told java the name of the class that you want to start!
I created in my current project folder the file .bash_profile with the content: export VAR_NAME=Value
That only affects new shell instances that are launched after you created the file. It doesn't affect the existing one.
I also created the folder .MacOSX with a single file inside environment.plist and in this file I wrote the property and its value using XCode.
I've no idea what that would do. Where did you create that folder?
1.open the Terminal
2.export VAR_NAME=Value
3.open /Applications/Eclipse.app