public Command()

in ClrMemDiag/Utilities/command.cs [394:519]
116 lines of code
24 McCabe index (conditional complexity)

        public Command(string commandLine, CommandOptions options)
        {
            _options = options;
            _commandLine = commandLine;

            // See if the command is quoted and match it in that case
            Match m = Regex.Match(commandLine, "^\\s*\"(.*?)\"\\s*(.*)");
            if (!m.Success)
                m = Regex.Match(commandLine, @"\s*(\S*)\s*(.*)");    // thing before first space is command

            ProcessStartInfo startInfo = new ProcessStartInfo(m.Groups[1].Value, m.Groups[2].Value);
            _process = new Process();
            _process.StartInfo = startInfo;
            _output = new StringBuilder();
            if (options.elevate)
            {
                options.useShellExecute = true;
                startInfo.Verb = "runas";
                if (options.currentDirectory == null)
                    options.currentDirectory = Environment.CurrentDirectory;
            }
            startInfo.CreateNoWindow = options.noWindow;
            if (options.useShellExecute)
            {
                startInfo.UseShellExecute = true;
                if (options.noWindow)
                    startInfo.WindowStyle = ProcessWindowStyle.Hidden;
            }
            else
            {
                if (options.input != null)
                    startInfo.RedirectStandardInput = true;
                startInfo.UseShellExecute = false;
                startInfo.RedirectStandardError = true;
                startInfo.RedirectStandardOutput = true;
                startInfo.ErrorDialog = false;
                startInfo.WindowStyle = ProcessWindowStyle.Hidden;
                startInfo.CreateNoWindow = true;

                _process.OutputDataReceived += new DataReceivedEventHandler(OnProcessOutput);
                _process.ErrorDataReceived += new DataReceivedEventHandler(OnProcessOutput);
            }

            if (options.environmentVariables != null)
            {
                // copy over the environment variables to the process startInfo options. 
                foreach (string key in options.environmentVariables.Keys)
                {
                    // look for %VAR% strings in the value and subtitute the appropriate environment variable. 
                    string value = options.environmentVariables[key];
                    if (value != null)
                    {
                        int startAt = 0;
                        for (; ;)
                        {
                            m = new Regex(@"%(\w+)%").Match(value, startAt);
                            if (!m.Success) break;
                            string varName = m.Groups[1].Value;
                            string varValue;
                            if (startInfo.EnvironmentVariables.ContainsKey(varName))
                                varValue = startInfo.EnvironmentVariables[varName];
                            else
                            {
                                varValue = Environment.GetEnvironmentVariable(varName);
                                if (varValue == null)
                                    varValue = "";
                            }
                            // replace this instance of the variable with its definition.  
                            int varStart = m.Groups[1].Index - 1;     // -1 becasue % chars are not in the group
                            int varEnd = varStart + m.Groups[1].Length + 2; // +2 because % chars are not in the group
                            value = value.Substring(0, varStart) + varValue + value.Substring(varEnd, value.Length - varEnd);
                            startAt = varStart + varValue.Length;
                        }
                    }
                    startInfo.EnvironmentVariables[key] = value;
                }
            }
            startInfo.WorkingDirectory = options.currentDirectory;

            _outputStream = options.outputStream;
            if (options.outputFile != null)
            {
                _outputStream = File.CreateText(options.outputFile);
            }

#if false
            if (options.showCommand && outputStream != null)
            {
                // TODO why only for output streams?
                outputStream.WriteLine("RUN CMD: " + commandLine);
            }
#endif
#if false
            // Make sure we kill this task when Ctrl C or appdomain unloads
            if (!options.noWait)
                AddCommandToCleanupList(this);
#endif
            try
            {
                _process.Start();
            }
            catch (Exception e)
            {
                string msg = "Failure starting Process\r\n" +
                    "    Exception: " + e.Message + "\r\n" +
                    "    Cmd: " + commandLine + "\r\n";

                if (Regex.IsMatch(startInfo.FileName, @"^(copy|dir|del|color|set|cd|cdir|md|mkdir|prompt|pushd|popd|start|assoc|ftype)", RegexOptions.IgnoreCase))
                    msg += "    Cmd " + startInfo.FileName + " implemented by Cmd.exe, fix by prefixing with 'cmd /c'.";
                throw new ApplicationException(msg, e);
            }

            if (!startInfo.UseShellExecute)
            {
                // startInfo asyncronously collecting output
                _process.BeginOutputReadLine();
                _process.BeginErrorReadLine();
            }

            // Send any input to the command 
            if (options.input != null)
            {
                _process.StandardInput.Write(options.input);
                _process.StandardInput.Close();
            }
        }