Set/Get Environment Variable from Java

Question

I am setting an Environmental Variable in a .sh script as following :

export enVAr=$(/sbin/ip route|awk '/default/ { print $3 }')

and to get that Environmental Variable in Java I run the script:

ProcessBuilder pb = new ProcessBuilder("./setEnvIP.sh");
Process p = pb.start();
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = null;
while ((line = reader.readLine()) != null)
{
    System.out.println(line);
}

but I get null for the env variable:

String setVar = System.getenv("enVAr");

How can I get the env variable?

Siyuan Ren · Accepted Answer · 2015-07-26 13:48:22Z

1

When you execute the script with ProcessBuilder, you start a new process and change the environmental variables associated with that child process. The environment of the original Java application thus remains unmodified.

You need to execute the script before launching JVM for the environment modification to be effective in the Java process.

answered Jul 26, 2015 at 13:48

Siyuan Ren

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kostya · Accepted Answer · 2015-07-26 13:48:50Z

1

In the example you provided the environment variable is set only for a child process (setEnvIP.sh) and its children. It is not not set in the parent java process.

As far as I know there is no way to set environment variable in Java for the current process. You can only modify environment for a child process using ProcessBuilder.environment(): http://docs.oracle.com/javase/7/docs/api/java/lang/ProcessBuilder.html#environment()

answered Jul 26, 2015 at 13:48

kostya

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