msbuild, how to set environment variables?

Question

I am trying to set environment variables using project file (ex. .vcxproj)

I looked at property functions but it didn't seem to have such function.

I know there is a way to retrieve environment variable but couldn't find how to set it.

I feel like there should be way to set environment variables in project file.

Answer 1

The coded task can be put right at the project file since MSBuild v4.0. Like this:

<UsingTask   TaskName="SetEnvironmentVariableTask"   TaskFactory="CodeTaskFactory"   AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v$(MSBuildToolsVersion).dll">    <ParameterGroup>     <Name ParameterType="System.String" Required="true" />     <Value ParameterType="System.String" Required="true" />   </ParameterGroup>    <Task>     <Using Namespace="System" />     <Code Type="Fragment" Language="cs">       <![CDATA[         Environment.SetEnvironmentVariable(Name, Value);       ]]>     </Code>   </Task>  </UsingTask> 

Note that in MSBuild 14+, the AssemblyFile reference should be just:

AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.Core.dll" 

The SetEnvironmentVariableTask can be then used from the target:

<Target Name="SampleTarget" BeforeTargets="Build">   <SetEnvironmentVariableTask Name="TEST_ENV_VAR" Value="$(MSBuildProjectName)" /> </Target> 

That's much handier than authoring a separate .DLL for small MSBuild task(s).

Answer 2

A couple of things:

1. If you are only using the variable in the context of MSBuild, then you can just use the standard MSBuild variables instead of trying to set an environment variable

2. If do need to set an env var, well, it's not an out-of-box thing. You need to write a custom task and then leverage it in the project file. Here's a link to an MSDN thread that outlines how to do this.
   How to set envrionment variables in MSBuild file?