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Struggling to pass a GitLab variable with multiple elements to a shell script? Explore effective techniques and tips in this comprehensive guide!
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How to Pass a GitLab Variable with Multiple Elements to a Shell Script Correctly

When working with GitLab CI/CD pipelines, you might encounter scenarios where you need to pass a variable containing multiple elements to a shell script. If you're facing issues with this, you're not alone! Let's break down the problem and explore how to effectively pass those variables without losing any data.

The Problem: Lost Elements

Imagine you've defined a GitLab variable as follows:

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

You intend to pass this variable to a shell script using:

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

While this seems straightforward, you may find that only the first element us-east-1 is captured when calling the script. Why does this happen? Let's understand it better.

Understanding Positional Parameters

When you run a command like test.sh $REGIONS, the shell interprets this in a specific way:

us-east-1 gets assigned to the first positional parameter $1

us-west-2 goes to $2

eu-central-1 is assigned to $3

However, if you want to treat REGIONS as a single entity (like a string), passing it directly might lead to unexpected behavior or loss of elements, since the shell splits them based on whitespace by default.

The Solution: Quoting the Variable

To solve the issue of losing additional elements, the simplest and most effective method is to quote your variable when invoking the shell script:

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

What Happens When You Quote the Variable?

By quoting "$REGIONS", you are treating the entire contents of the variable as a single string, which provides a more reliable outcome. Here’s how it changes the behavior:

When you call test.sh "$REGIONS", the entire string us-east-1 us-west-2 eu-central-1 is assigned to the first positional parameter $1 in the script, allowing you to retain all necessary data.

Accessing All Arguments

If you decide to go ahead with positional parameters, you can still access all elements in the script using $@ , which will include all passed arguments. However, for simplicity and to avoid potential errors, quoting the variable is recommended.

Conclusion

Passing multi-element variables in GitLab CI/CD directly to shell scripts can be tricky if you aren’t careful. Remember, whenever you have a variable that contains spaces (like the list of regions in our example), always use quotes when passing them to avoid losing any part of the data. By following this guide, you can effectively convey multiple elements in a neatly structured manner. Happy scripting!