System.Environment class does not have a method to set the environment variable for the current process (829145)
The information in this article applies to:
- Microsoft .NET Framework 2.0
- Microsoft .NET Framework 1.1
- Microsoft .NET Framework 1.0
- Microsoft Visual C# 2005, Express Edition
- Microsoft Visual C# .NET (2003)
- Microsoft Visual C# .NET (2002)
- Microsoft Visual Basic 2005
- Microsoft Visual Basic .NET (2003)
- Microsoft Visual Basic .NET (2002)
SYMPTOMSThe System.Environment class has methods to read the
environment variables. However, this class has no method to set the environment variables
for the current process.WORKAROUNDTo work around this problem, use the interop services to set
the environment variables. You can set an
environment variable by using the Microsoft Platform Software Development Kit (SDK)
SetEnvironmentVariable function. To set an environment variable by calling the Platform SDK SetEnvironmentVariable function, follow these steps:
- Start Microsoft Visual Studio 2005 or Microsoft Visual Studio .NET.
- On the File menu, point to
New, and then click New Project.
- In the New Project dialog box, click
Visual C# Projects.
Note In Visual Studio 2005, Visual C# Projects is be changed to Visual C#. - Under Templates, click
Console Application, and then click OK. By
default, the Class1.cs file is created.
- In the code view of the Class1.cs file,
specify the using statement to declare the namespaces so that you do not have to
qualify the declarations later in the code. Paste the following code in the Class1.cs file:
using System;
using System.Runtime.InteropServices;
using System.Security;
using System.Security.Permissions;
- Declare the static method and the extern method. Use the DllImport attribute to import the Kernel32.dll file. This declaration indicates that the definition of the function
is outside the code. To do this, paste the following code in the Class1.cs file:
// Import the Kernel32 dll file.
[DllImport("kernel32.dll",CharSet=CharSet.Auto, SetLastError=true)]
[return:MarshalAs(UnmanagedType.Bool)]
// The declaration is similar to the SDK function
public static extern bool SetEnvironmentVariable(string lpName, string lpValue);
- Paste the following code in the Class1.cs file to add a static method in the
class that calls the SetEnvironmentVariable method and that sets the environment variable:
public static bool SetEnvironmentVariableEx(string environmentVariable, string variableValue)
{
try
{
// Get the write permission to set the environment variable.
EnvironmentPermission environmentPermission = new EnvironmentPermission(EnvironmentPermissionAccess.Write,environmentVariable);
environmentPermission.Demand();
return SetEnvironmentVariable(environmentVariable, variableValue);
}
catch( SecurityException e)
{
Console.WriteLine("Exception:" + e.Message);
}
return false;
} - Paste the following code in the Main method to set an
environment variable:
// Create a sample environment variable and set its value (for the current process).
SampleSetEnvironmentVariable.SetEnvironmentVariableEx("TESTENV", "TestValue");
- Paste the following code to display the environment
variable value:
// Verify that environment variable is set correctly.
Console.WriteLine("The value of TESTENV is: " + Environment.GetEnvironmentVariable("TESTENV"));
Complete Code Sampleusing System;
using System.Runtime.InteropServices;
using System.Security;
using System.Security.Permissions;
namespace SetEnv
{
/// <summary>
/// Summary description for Class1.
/// </summary>
public class SampleSetEnvironmentVariable
{
// Import the kernel32 dll.
[DllImport("kernel32.dll",CharSet=CharSet.Auto, SetLastError=true)]
[return:MarshalAs(UnmanagedType.Bool)]
// The declaration is similar to the SDK function
public static extern bool SetEnvironmentVariable(string lpName, string lpValue);
public SampleSetEnvironmentVariable()
{
}
public static bool SetEnvironmentVariableEx(string environmentVariable, string variableValue)
{
try
{
// Get the write permission to set the environment variable.
EnvironmentPermission environmentPermission = new EnvironmentPermission(EnvironmentPermissionAccess.Write,environmentVariable);
environmentPermission.Demand();
return SetEnvironmentVariable(environmentVariable, variableValue);
}
catch( SecurityException e)
{
Console.WriteLine("Exception:" + e.Message);
}
return false;
}
}
class MyClass
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main(string[] args)
{
// Create a sample environment variable and set its value (for the current process).
SampleSetEnvironmentVariable.SetEnvironmentVariableEx("TESTENV", "TestValue");
// Verify that environment variable is set correctly.
Console.WriteLine("The value of TESTENV is: " + Environment.GetEnvironmentVariable("TESTENV"));
}
}
} STATUS Microsoft
has confirmed that this is a problem in the Microsoft products that are listed
at the beginning of this article.
REFERENCESFor more information, visit the following Microsoft Developer Network (MSDN) Web
sites:
Modification Type: | Minor | Last Reviewed: | 10/3/2006 |
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Keywords: | kbvs2005applies kbvs2005swept kbprb kbenv kbCOMInterop KB829145 kbAudDeveloper |
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