Verifying that the process returned an error | FROM#

Question

After announcing and starting the process, as shown below:

System.Diagnostics.Process _p = new System.Diagnostics.Process(); ..... ..... .... _p.Start(); 

Now there are two possibilities: either an exit or an error.

If an error occurs, is there any property of the Process class to find out if an error has occurred?

I redirect standard output, I do not want to redirect standard error as warned on MSDN . Also I do not want to use: BeginOutputReadLine();

Are there any alternatives?

Thanks.

Answer 1

I have a service that needs to start processes and wait for them to exit, and I use something like:

 process.Start(); int timeout = ... // some normal value in milliseconds process.WaitForExit(timeout); try { //ExitCode throws if the process is hanging return (CommandErrorCode)process.ExitCode; } catch (InvalidOperationException ioex) { return CommandErrorCode.InternalError; } 

where CommandErrorCode is something like

 public enum CommandErrorCode { Success = 0, //some other values I know from the processes that are managed InternalError = 256 // the ExitCode is a byte, so this out of that range } 

Btw, I redirect both standard output and standard error and use the BeginXXXReadLine and XXXDataReceived handlers and I have no problems, but the processes I use are known, well defined and well behaved.

Answer 2

Here is a code snippet, hope this helps

http://ss64.com/nt/cmd.html for reference cmd.exe

 private int CallShell(string exeCommand, string Parameters)        {            //http://ss64.com/nt/cmd.html            /*            This function will actually take the shell string and envoke the appropriate process             passing it the arguments to do the work            */            // Initialize the process and its StartInfo properties.            System.Diagnostics.Process ProcessEXE = new System.Diagnostics.Process();            logger.DebugFormat("About to Start Process - {0} {1}",exeCommand, Parameters);            try            {                ProcessEXE.StartInfo.FileName = exeCommand;                // Set UseShellExecute to false for redirection.                //  false if the process should be created directly from the executable file                ProcessEXE.StartInfo.UseShellExecute = false;                ProcessEXE.StartInfo.WorkingDirectory = System.Environment.CurrentDirectory;                //EnableRaisingEvents property indicates whether the component should be notified when the operating system has shut down a process                ProcessEXE.StartInfo.Arguments = Parameters;                ProcessEXE.StartInfo.RedirectStandardOutput = true;                ProcessEXE.StartInfo.RedirectStandardError = true;                ProcessEXE.EnableRaisingEvents = true;                ProcessEXE.StartInfo.CreateNoWindow = true;                ProcessEXE.OutputDataReceived += new System.Diagnostics.DataReceivedEventHandler(ProcessEXE_OutputDataReceived);                ProcessEXE.ErrorDataReceived += new System.Diagnostics.DataReceivedEventHandler(ProcessEXE_OutputDataReceived);                logger.DebugFormat("Process Started.");                ProcessEXE.Start();                // Start the asynchronous read of the sort output stream.                ProcessEXE.BeginErrorReadLine();                ProcessEXE.BeginOutputReadLine();                //The WaitForExit overload is used to make the current thread wait until the associated process terminates                logger.DebugFormat("Process Waiting for exit.");                ProcessEXE.WaitForExit();                if (ProcessEXE.ExitCode == 0)                {                    logger.Debug(string.Format("Shell Process exited with exit code {0}", ProcessEXE.ExitCode));                }                else                { // throw error here if required - check the return error code                    logger.Warn(string.Format("Shell Process exited with exit code {0}", ProcessEXE.ExitCode));                }            }            catch (Exception ex)            {                throw new Exception(string.Format("Method:{0}", ex.TargetSite), ex);            }            return ProcessEXE.ExitCode;        } void ProcessEXE_OutputDataReceived(object sender, System.Diagnostics.DataReceivedEventArgs e)        {            try            {                StringBuilder sb = new StringBuilder(string.Empty);                if (e == null) return;                if (e.Data == null)                {                    //No processing                }                else                {                   // your logic to detect error msg out from output - if at all required                }                if (sb.ToString().ToUpper().IndexOf("ERROR") > 0)                {                    string smessage = "Error text found in  output."; // do your error response action here .                }            }            catch (Exception exp)            {                logger.ErrorFormat("Error in ProcessEXE_OutputDataReceived Message:{0}", exp.Message);                logger.ErrorFormat("Error in ProcessEXE_OutputDataReceived Data Received:{0}", e.Data); // either throw error msg or kill the process            }            finally            {                // Not throwing the exception            }        }