Executing custom commands from command prompt in winform C#

Try to extract the Working directory from your command and set the WorkingDirectory property for the ProcessStartInfo object. Then in your command pass only the filename.

This example assumes that command contains only the full filename.
Need to be adjusted for your actual command text

string command = "C:\Documents and settings\mytestapp\tools\mycommand.exe";
string parameters = "parameter1 parameter2";

try
{
    string workDir = Path.GetDirectoryName(command);
    string fileCmd = Path.GetFileName(command);
    System.Diagnostics.ProcessStartInfo procStartInfo =
        new System.Diagnostics.ProcessStartInfo("cmd", "/c " + fileCmd + " " + parameters);
    procStartInfo.WorkingDirectory = workDir;
    procStartInfo.RedirectStandardOutput = true;
    procStartInfo.UseShellExecute = false;
    procStartInfo.CreateNoWindow = true;
    System.Diagnostics.Process proc = new System.Diagnostics.Process();
    proc.StartInfo = procStartInfo;
    proc.Start();
    proc.WaitForExit();
}
catch (Exception objException)
{
    // Log the exception
}

I believe the following works: "C:\Documents and settings\mytestapp\tools\mycommand.exe" "parameter1" "parameter2"

You may have something else wrong. Try to debug and check whether quote is used twice, or if there are quotes in the middle.

I think it could be because quotes are needed in args (and command) strings that refer to paths that contain whitespace; also they need to be escaped when defined non-verbatim (i.e. no @ preceding the string) in-code, so the command string would be defined like this:

var command = "\"C:\\Documents and settings\\mytestapp\\tools\\mycommand.exe\"";
             // ^ escaped quote                                              ^ escaped quote

Specifically for starting processes I wrote this method not long ago, it could be a little bit too specialized for this specific case, but one could easily take it as is and/or write overloads with different parameters for different flavors of setting up a process:

private ProcessStartInfo CreateStartInfo(string command, string args, string workingDirectory, bool useShellExecute)
{
    var defaultWorkingDirectory = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location) ?? string.Empty;
    var result = new ProcessStartInfo
    {
        WorkingDirectory = string.IsNullOrEmpty(workingDirectory) 
                                 ? defaultWorkingDirectory 
                                 : workingDirectory,
        FileName = command,
        Arguments = args,
        UseShellExecute = useShellExecute,
        CreateNoWindow = true,
        ErrorDialog = false,
        WindowStyle = ProcessWindowStyle.Hidden,
        RedirectStandardOutput = !useShellExecute,
        RedirectStandardError = !useShellExecute,
        RedirectStandardInput = !useShellExecute
    };
    return result;
}

I'm using it like below; here the _process object could be any Process - having it as an instance variable might not be valid for your use case; also the OutputDataReceived and ErrorDataReceived event handlers (not shown) only log the output string - but you could parse it and base some course of action upon it:

public bool StartProcessAndWaitForExit(string command, string args, 
                     string workingDirectory, bool useShellExecute)
{
    var info = CreateStartInfo(command, args, workingDirectory, useShellExecute);            
    if (info.RedirectStandardOutput) _process.OutputDataReceived += _process_OutputDataReceived;
    if (info.RedirectStandardError) _process.ErrorDataReceived += _process_ErrorDataReceived;

    var logger = _logProvider.GetLogger(GetType().Name);
    try
    {
        _process.Start(info, TimeoutSeconds);
    }
    catch (Exception exception)
    {
        logger.WarnException(log.LogProcessError, exception);
        return false;
    }

    logger.Debug(log.LogProcessCompleted);
    return _process.ExitCode == 0;
}

The args string you pass is exactly how you would enter it at the command-line, so in your case that might look like:

CreateStartInfo("\"C:\\Documents and settings\\mytestapp\\tools\\mycommand.exe\"", 
                "-switch1 -param1:\"SomeString\" -param2:\"Some\\Path\\foo.bar\"",
                string.Empty, true);

If you instead put the path/command strings in a settings file, you can store them without needing to escape quotes and backslashes.