How do I use custom variables in MSBuild scripts?

Question

Is there a way to use custom variables on the command-line when building with MSBuild.exe as follows:

MSBuild.exe bootstrapper.msbuild <custom_variable1=custom_variable_value1>

custom_variable2=custom_variable_value2>...<custom_variablen=custom_variable_valuen>

The purpose is to know whether I have to launch another executable or not.

Answer 1

You should start with the basics. The answer is found in the official documentation.

MSBuild calls these properties instead of variables.

In practice:

msbuild bootstrapper.msbuild /p:custom_variable1=custom_variable_value1

And in the MSBuild file you could use it as such:

<Target Name="MyTarget">
  <PropertyGroup>
    <custom_variable1 Condition="'$(custom_variable1)'==''">defaultValue</custom_variable1>
  </PropertyGroup>
  <Exec Condition="'$(custom_variable1)'=='someValue'" .../>
</Target>

This assigns a default value to the property if it doesn't exist or is empty, and only executes the Exec task if the value is equal to someValue.