@gurikbal-singh Even when I set useShellExecute to false, the python script is still not being invoked. The txt file that my python script is supposed to generate cannot be found anywhere. Any advice on how to resolve this issue?

proc.StartInfo.Arguments = string.Concat(progToRun, " ", s)

         try
        {
            Process Process = new Process();
            string keyValues = currentDirectory() + "\\User_Command_Line_Tools_PATH";
            string keyValue = currentDirectory() + "\\GnuWin32\\bin";
            string envVar = Process.StartInfo.EnvironmentVariables["path"];
            if (envVar != null)
            {
                string value = envVar + ";" + keyValue + ";" + keyValues;
                Process.StartInfo.EnvironmentVariables["path"] = value;
            }
            else
            {
                Process.StartInfo.EnvironmentVariables.Add("path", keyValue);
                Process.StartInfo.EnvironmentVariables.Add("path", keyValues);
            }
            Process.StartInfo.FileName = windir() + "\\cmd.exe";
            Process.StartInfo.Arguments = "/c " + richTextBox1.Text;
            if (filepath().ToString() == filex().ToString())
            {
                Process.StartInfo.WorkingDirectory = currentDirectory() + "\\GnuWin32\\bin";
            }
            else
            {
                Process.StartInfo.WorkingDirectory = path.ToString();
            }
            Process.StartInfo.RedirectStandardError = true;
            Process.StartInfo.RedirectStandardOutput = true;
            Process.StartInfo.RedirectStandardInput = true;
            Process.StartInfo.UseShellExecute = false;
            Process.StartInfo.CreateNoWindow = true;
            Process.Start();
            string lined = Process.StandardOutput.ReadToEnd();
            string line = Process.StandardError.ReadToEnd();
            if (String.IsNullOrEmpty(lined))
            {
                richTextBox2.AppendText(line + Environment.NewLine);
            }
            if (String.IsNullOrEmpty(line))
            {
                richTextBox2.AppendText(lined + Environment.NewLine);
            }
            Process.WaitForExit();
            if (checkBox2.Checked == true)
            {
                Win32.SendMessage(PluginBase.GetCurrentScintilla(), SciMsg.SCI_SETTEXT, 0, richTextBox2.Text);
            }

        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.Write(ex.Message);
        }

No, i was referring to the one @PeterJones mentioned.

are you referring to PyNPP

The Python Script plugin is not PyNPP (which I had not heard of until now). It is a plugin which embeds a full Python 2.7 interpreter inside the Notepad++ environment, and allows you to run a script from within Notepad++ that gives Python direct access to the contents of all the files open in Notepad++, along with access to many aspects of the Notepad++ GUI.

For instructions on how to install the Python Script in Notepad++ v7.6.3 and later, see this Guide by @Meta-Chuh (because, unfortunately, Python Script plugin doesn’t currently install using the Plugins Admin interface).

Just curious, you know that there is a python script plugin available, don’t you?

proc.StartInfo.UseShellExecute = false;