在shell脚本中设置环境变量并在Java程序中访问

Question

This question is a followup on Set environment variable in shell script/access in Java program . I am trying to fetch the environment variable in Java after running a shell script but unable to do so

Shell Script: getDetails.sh:

#!/bin/bash
# File: getDetails.sh
export userDetails="USER123"
# echo "User Details for App :$userDetails"

Java method:

String details = new String("source " + "getDetails.sh");
ProcessBuilder processBuilder = new ProcessBuilder("/bin/bash", "-c", details);
Process getPwdProc = processBuilder.start();
System.out.println("Details - " + processBuilder.environment().get("userDetails"));

The java method returns/prints null for the environment variable - userDetails.

PS - Please note that the use of InputStream/BufferedReader to read the userDetails is not possible here as echoing the details is not allowed for the program/organization.

Answer 1

Exporting an environment variable from a bash process does not make it "global", it means that it is inherited (copied) to child processes. That is, processes run by the bash process which exported it.

Here Java is the parent , and there is no (legal) way to inject a variable into a parent process from a child. The variable has to be set and exported before the Java is run.

I suggest a "wrapper" bash script that first exports the variable and then runs your Java application.