Set environment variables for a process

Question

What is the environment variable concept?

In a C# program I need to call an executable. The executable will call some other executables that reside in the same folder. The executables rely on the two environment variables "PATH" and "RAYPATH" to be set correctly. I tried the following two things:

1. I created a process and set the two varables in StartInfo. The variables exist already but are missing the needed information.
2. I tried to set the variables with System.Environment.SetEnvironmentVariable().

When I run the process the system can't find the executable ("executeable1"). I tried to set StartInfo.FileName to the full path of "executeable1" - however then the EXE files called form within "executeable1" are not found...

How do I deal with this?

string pathvar = System.Environment.GetEnvironmentVariable("PATH");
System.Environment.SetEnvironmentVariable("PATH", pathvar + @";C:\UD_\bin\DAYSIM\bin_windows\;C:\UD_\bin\Radiance\bin\;C:\UD_\bin\DAYSIM;");
System.Environment.SetEnvironmentVariable("RAYPATH", @"C:\UD_\bin\DAYSIM\lib\;C:\UD_\bin\Radiance\lib\");

System.Diagnostics.Process p = new System.Diagnostics.Process();
p.StartInfo.WorkingDirectory = @"C:\UD_\bin\DAYSIM\bin_windows";

//string pathvar = p.StartInfo.EnvironmentVariables["PATH"];
//p.StartInfo.EnvironmentVariables["PATH"] = pathvar + @";C:\UD_\bin\DAYSIM\bin_windows\;C:\UD_\bin\Radiance\bin\;C:\UD_\bin\DAYSIM;";
//p.StartInfo.EnvironmentVariables["RAYPATH"] = @"C:\UD_\bin\DAYSIM\lib\;C:\UD_\bin\Radiance\lib\";


p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.CreateNoWindow = true;

p.StartInfo.FileName = "executeable1";
p.StartInfo.Arguments = arg1 + " " + arg2;
p.Start();
p.WaitForExit();

Answer 1

What is your problem actually? System.Environment.SetEnvironmentVariable changes the environment variables of the current process. If you want to change the variables of a process you create, just use the EnvironmentVariables dictionary property:

var startInfo = new ProcessStartInfo();

// Sets RAYPATH variable to "test"
// The new process will have RAYPATH variable created with "test" value
// All environment variables of the created process are inherited from the
// current process
startInfo.EnvironmentVariables["RAYPATH"] = "test";

// Required for EnvironmentVariables to be set
startInfo.UseShellExecute = false;

// Sets some executable name
// The executable will be search in directories that are specified
// in the PATH variable of the current process
startInfo.FileName = "cmd.exe";

// Starts process
Process.Start(startInfo);