I am able to run a sample hadoop program from the command prompt and am trying to run the same program from Eclipse, so that I can debug it and understand it better.
For the command line program, some environment variables are set in the .bashrc
and the same are being read as System.getenv().get("HADOOP_MAPRED_HOME")
in the hadoop program. But, when I am running a java program with System.getenv().get("HADOOP_MAPRED_HOME")
, from Eclipse I am getting null.
I tried passing -DHADOOP_MAPRED_HOME=test
to VM parameters in the runtime configurations from Eclipse, but still getting null in the standalone program. How to make the environment variables visible within Eclipse? When I iterate through System.getenv()
in Eclipse, I see lot of variables like DISPLAY
, USER
, HOME
and others. Where are they set? I am using Ubuntu 11.04.
If you're askign where Eclipse stores the values on a per-project basis, the answer is in the . classpath file.
Variables/Expression view – Shows the declared variables and their values. Press Ctrl+Shift+d or Ctrl+Shift+i on a selected variable or expression to show its value. You can also add a permanent watch on an expression/variable that will then be shown in the Expressions view when debugging is on.
On the Windows taskbar, right-click the Windows icon and select System. In the Settings window, under Related Settings, click Advanced system settings. On the Advanced tab, click Environment Variables.
You can also define an environment variable that is visible only within Eclipse.
Go to Run -> Run Configurations... and Select tab "Environment".
There you can add several environment variables that will be specific to your application.
I've created an eclipse plugin for this, because I had the same problem. Feel free to download it and contribute to it.
It's still in early development, but it does its job already for me.
https://github.com/JorisAerts/Eclipse-Environment-Variables
The .bashrc file is used for setting variables used by interactive login shells. If you want those environment variables available in Eclipse you need to put them in /etc/environment.
You can set the Hadoop home directory by sending a -Dhadoop.home.dir to the VM. To send this parameters to all your application that you execute inside eclipse, you can set them in Window->Preferences->Java->Installed JREs-> (select your JRE installation) -> Edit.. -> (set the value in the "Default VM arguments:" textbox). You can replace ${HADOOP_HOME} with the path to your Hadoop installation.
You can also start eclipse within a shell.
You export the enronment, before calling eclipse.
Example :
#!/bin/bash
export MY_VAR="ADCA"
export PATH="/home/lala/bin;$PATH"
$ECLIPSE_HOME/eclipse -data $YOUR_WORK_SPACE_PATH
Then you can have multiple instances on eclipse with their own custome environment including workspace.
I was trying to achieve this but in the context of a MAVEN build. As part of my pom.xml
configuration, I had a reference to an environment variable as part of a path to a local JAR:
<dependency>
<groupId>the group id</groupId>
<artifactId>the artifact id</artifactId>
<version>the version</version>
<scope>system</scope>
<systemPath>${env.MY_ENV_VARIABLE}/the_local_jar_archive.jar</systemPath>
</dependency>
To compile my project, I had to define the environment variable as part of the run configuration for the maven build as explained by Max's answer. I was able to launch the maven compilation and the project would compile just fine.
However, as this environment variable involves some dependencies, the default "problems" view of Eclipse (where compilation errors/warnings usually show) would still show errors along the lines of Could not find artifact
and systemPath should be an absolute path but is ${env.MY_ENV_VARIABLE}/the_local_jar_archive.jar
.
How I fixed it
Go into Window -> Preferences -> General -> Worksapce -> Linked Resources
and define a new path variable.
Finally, in my case I just needed to Right click on my pom.xml
file, select Maven -> Update Project
and the errors disappeared from the "Problems" view.
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