How to Run PowerShell or Shell Scripts from CMake

Learn how to execute PowerShell and Shell scripts during CMake build processes effectively. This guide provides step-by-step instructions and solutions for common issues you may encounter.
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Running PowerShell or Shell Scripts from CMake

When building projects, automating tasks can save you a lot of time and effort. One common requirement is to run scripts, such as PowerShell or Shell scripts, during the build process. This is particularly useful when a script is needed to generate files, like version headers, which your project depends on. This guide discusses how to seamlessly integrate these scripts into your CMake project and addresses a common issue you might encounter.

The Challenge

In this scenario, you have a PowerShell script that generates a version file, version.h, which is necessary for other parts of your project. Below is an outline of the initial attempt at a solution:

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While attempting to use this method, you encounter an error:

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This error often indicates that the command being executed couldn’t be found or that there's an issue with the executable path or format.

The Solution

To fix the issue and allow your CMake build to correctly run the PowerShell script, consider the following approach, which involves finding the PowerShell executable specifically and invoking it to run your command.

Step 1: Find the PowerShell Executable

First, you need to confirm that the PowerShell executable can be located within your build environment. You can use find_program for that purpose.

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This line will set the variable POWERSHELL_PATH to the location of the PowerShell executable if it's found.

Step 2: Use add_custom_command Effectively

Next, you will use add_custom_command to run the PowerShell command post-build. Instead of directly calling the script, you can call PowerShell with the script as an argument:

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Explanation of Key Components

find_program: This CMake function searches for the executable and can help avoid issues of directly referencing the script without knowing the correct shell environment.

add_custom_command: This command allows you to specify a shell command to execute as a part of the build process, which is why integrating PowerShell at this point is beneficial.

Post-build: The POST_BUILD option makes sure that the command runs after the build of the specified target (in this case called “program”).

Important Points to Remember

Ensure that your PowerShell script is executable and that the path is correct.

When using arguments in CMake for PowerShell, use quotes appropriately to handle any spaces or special characters.

If you still encounter issues after implementing these changes, double-check the command and script paths, and ensure that you have the necessary permissions to execute the script.

Conclusion

Incorporating PowerShell or Shell scripts into your CMake workflows may initially present challenges, such as the Error 193 encountered. However, by utilizing the find_program function and correctly structuring the add_custom_command, you can effectively automate script execution in your build process. This guide should help you troubleshoot and successfully run your scripts for various tasks, enhancing your project's efficiency and maintainability.

For any further queries or insights about CMake and script integration, feel free to leave comments below!