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Resolving Bash Script Execution Issues in Linux on Unity Build Automation

Updated

This article addresses the issue of running bash scripts via C# IPreProcessBuildWithReport in Unity Build Automation (UBA). The problem arises due to file permissions and the execution method within a Linux-based UBA environment. The resolution involves modifying the C# script to call the shell interpreter explicitly and ensuring the script has execute permissions.

 

Symptoms:

  • You get the following exception:

    Win32Exception: ApplicationName='/BUILD_PATH/.../build.sh', Native error= Access denied
  • Bash scripts work locally but fail in UBA.

 

Cause:

The issue is caused by file permissions and the way shell scripts are executed in a Linux-based UBA environment. The scripts must have execute permissions and should be run through an interpreter such as bash.

 

Resolution:

Firstly, we suggest using the UBA's built-in script hooks for pre and post-build bash scripts.

Here is the recommended approach, which simplifies the build process and aligns it with UBA’s intended workflow:

  • Keep the build.sh script in your repository.
  • In the UBA Dashboard, navigate to your build target’s Advanced Settings.
  • Enter the path to your script in the 'Pre-build script' path field (e.g., build.sh).
  • Remove the IPreprocessBuildWithReport C# script.

If, for some reason, the steps above don't work for your use case, here is what you can try:

1. Create a C# pre-build script with a RunExecutable method that differentiates between platforms:

private bool RunExecutable(string executablePath, string args, string workingDirectory) {
    var process = new Process();
    var workingDirectoryFullPath = Path.GetFullPath(workingDirectory);
    try {
        if (Application.platform == RuntimePlatform.WindowsEditor) {
            process.StartInfo.FileName = executablePath;
            process.StartInfo.Arguments = args;
        } else {
            process.StartInfo.FileName = "/bin/bash";
            process.StartInfo.Arguments = $"\"{executablePath}\" {args}";
        }
        process.StartInfo.WorkingDirectory = workingDirectoryFullPath;
        process.StartInfo.UseShellExecute = false;
        process.StartInfo.RedirectStandardOutput = true;
        process.StartInfo.RedirectStandardError = true;
        process.StartInfo.CreateNoWindow = true;
        process.OutputDataReceived += (_, e) => {
            if (e.Data != null) {
                LogHelper.Log($"RunCommand: {e.Data}", this);
            }
        };
        process.ErrorDataReceived += (_, e) => {
            if (e.Data != null) {
                LogHelper.Error($"RunCommand: {e.Data}", this);
            }
        };
        process.Start();
        process.BeginOutputReadLine();
        process.BeginErrorReadLine();
        process.WaitForExit();
        return process.ExitCode == 0;
    } catch (System.Exception ex) {
        LogHelper.Error($"Failed to run command in '{workingDirectoryFullPath}'", this);
        LogHelper.Exception(ex, this);
        return false;
    } finally {
        process.Dispose();
    }
}

2. If you are using Git, ensure your build script is executable in the UBA environment:

git update-index --chmod=+x build.sh

 

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