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Learn how to effectively get environment variable values from another user in Oracle Linux 7 for your bash scripts. This guide will break down the steps for isolating the desired variable value without unwanted output.
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How to Retrieve Environment Variables from Another User in Oracle Linux 7 Bash Scripts

When working with Oracle Linux 7, particularly within the Oracle E-Business Suite R12 environment, there might come a time when you need to access environment variables belonging to another user. This can be quite tricky if you are writing a bash script and want to assign the value of an environment variable from one user to a local variable in your script. In this article, we will explain how to achieve that effectively.

The Problem

You have a bash script that runs as the root user, and you need to extract the value of an environment variable (like RUN_BASE) set by another user, applmgr. You initially attempted to echo the variable directly but found the output was cluttered with additional content from the environment file being sourced.

Your Initial Attempt

Here’s what you started with:

[[See Video to Reveal this Text or Code Snippet]]

This command worked fine, but when you tried assigning it to a local variable, you ended up with unwanted outputs:

[[See Video to Reveal this Text or Code Snippet]]

The goal is to isolate the value of RUN_BASE without the extra outputs from the environment file.

The Solution

To retrieve only the necessary environment variable without the additional outputs, you need to redirect the standard output and standard error of the source command to /dev/null. Here’s how you can do it:

Step-by-Step Breakdown

Using su Command: First, you will continue using the su command to switch to the applmgr user.

Sourcing Environment File: You need to source the environment file to load the variables, but you don't want to see any errors or other outputs during this process.

Redirection: Redirect the combined standard output and standard error of the source command to /dev/null. This makes it so that only the output from the echo command is returned.

Echoing Variable: After sourcing the file, you will simply echo the value you want.

Final Command

Putting all of these steps together, your final command would look like this:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Command

su applmgr -c '...': Switch to the applmgr user and execute the command within the quotes.

source /u02/oracle/apps/EBSapps.env run >/dev/null 2>&1: This sources the environment file and sends all output (both stdout and stderr) to /dev/null, meaning it will not be displayed or captured.

echo "$RUN_BASE": This part outputs the value of the RUN_BASE variable which you want to capture.

Conclusion

Using the above approach, you can effectively isolate the environment variable value you need without any unnecessary clutter. This method is particularly useful in scripting when you want to ensure clean and manageable outputs.

By following these steps, you should be able to get the RUN_BASE environment variable assigned to your BASE_PATH variable with minimal fuss in your Oracle Linux 7 bash scripts.