dotnet-installer/old/build_projects/dotnet-cli-build/SetEnvVar.cs

// Copyright (c) .NET Foundation and contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;
using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;

namespace Microsoft.DotNet.Cli.Build
{
    public class SetEnvVar : Task
    {
        [Required]
        public string Name { get; set; }

        [Required]
        public string Value { get; set; }

        public override bool Execute()
        {
            Environment.SetEnvironmentVariable(Name, Value);

            return true;
        }
    }
}