Process start how to get the output

Question

I would like to run an external command line program from my Mono  NET app   For example  I would like to run mencoder  Is it possible    To get the command line shell output  and write it on my text box  To get the numerical value to show a progress bar with time elapsed

User · Answer

you can use shared memory for the 2 processes to communicate through, check out MemoryMappedFile

you'll mainly create a memory mapped file mmf in the parent process using "using" statement then create the second process till it terminates and let it write the result to the mmf using BinaryWriter, then read the result from the mmf using the parent process, you can also pass the mmf name using command line arguments or hard code it.

make sure when using the mapped file in the parent process that you make the child process write the result to the mapped file before the mapped file is released in the parent process

Example: parent process

    private static void Main(string[] args)
    {
        using (MemoryMappedFile mmf = MemoryMappedFile.CreateNew("memfile", 128))
        {
            using (MemoryMappedViewStream stream = mmf.CreateViewStream())
            {
                BinaryWriter writer = new BinaryWriter(stream);
                writer.Write(512);
            }

            Console.WriteLine("Starting the child process");
            // Command line args are separated by a space
            Process p = Process.Start("ChildProcess.exe", "memfile");

            Console.WriteLine("Waiting child to die");

            p.WaitForExit();
            Console.WriteLine("Child died");

            using (MemoryMappedViewStream stream = mmf.CreateViewStream())
            {
                BinaryReader reader = new BinaryReader(stream);
                Console.WriteLine("Result:" + reader.ReadInt32());
            }
        }
        Console.WriteLine("Press any key to continue...");
        Console.ReadKey();
    }

Child process

    private static void Main(string[] args)
    {
        Console.WriteLine("Child process started");
        string mmfName = args[0];

        using (MemoryMappedFile mmf = MemoryMappedFile.OpenExisting(mmfName))
        {
            int readValue;
            using (MemoryMappedViewStream stream = mmf.CreateViewStream())
            {
                BinaryReader reader = new BinaryReader(stream);
                Console.WriteLine("child reading: " + (readValue = reader.ReadInt32()));
            }
            using (MemoryMappedViewStream input = mmf.CreateViewStream())
            {
                BinaryWriter writer = new BinaryWriter(input);
                writer.Write(readValue * 2);
            }
        }

        Console.WriteLine("Press any key to continue...");
        Console.ReadKey();
    }

to use this sample, you'll need to create a solution with 2 projects inside, then you take the build result of the child process from %childDir%/bin/debug and copy it to %parentDirectory%/bin/debug then run the parent project

childDir and parentDirectory are the folder names of your projects on the pc good luck :)

User · Answer

You can log process output using below code   ProcessStartInfo pinfo   new ProcessStartInfo item   pinfo CreateNoWindow   false  pinfo UseShellExecute   true  pinfo RedirectStandardOutput   true  pinfo RedirectStandardInput   true  pinfo RedirectStandardError   true  pinfo WindowStyle   System Diagnostics ProcessWindowStyle Normal  var p   Process Start pinfo   p WaitForExit    Process process   Process Start new ProcessStartInfo  item     gt     item     txt          UseShellExecute   false      RedirectStandardOutput   true     process WaitForExit    string output   process StandardOutput ReadToEnd    if  process ExitCode    0

User · Answer

The standard  NET way of doing this is to read from the Process  StandardOutput stream  There is an example in the linked MSDN docs  Similar  you can read from StandardError  and write to StandardInput

User · Answer

Alright  for anyone who wants both Errors and Outputs read  but gets deadlocks with any of the solutions  provided in other answers  like me   here is a solution that I built after reading MSDN explanation for StandardOutput property   Answer is based on T30 s code   static void runCommand             Create your Process     Process process   new Process        process StartInfo FileName    cmd exe       process StartInfo Arguments     c DIR       process StartInfo UseShellExecute   false      process StartInfo RedirectStandardOutput   true      process StartInfo RedirectStandardError   true          Set ONLY ONE handler here      process ErrorDataReceived    new DataReceivedEventHandler ErrorOutputHandler           Start process     process Start            Read one element asynchronously     process BeginErrorReadLine            Read the other one synchronously     string output   process StandardOutput ReadToEnd        Console WriteLine output       process WaitForExit       static void ErrorOutputHandler object sendingProcess  DataReceivedEventArgs outLine             Do your stuff with the output  write to console log StringBuilder      Console WriteLine outLine Data

User · Answer

When you create your Process object set StartInfo appropriately   var proc   new Process        StartInfo   new ProcessStartInfo               FileName    program exe           Arguments    command line arguments to your executable           UseShellExecute   false          RedirectStandardOutput   true          CreateNoWindow   true            then start the process and read from it   proc Start    while   proc StandardOutput EndOfStream        string line   proc StandardOutput ReadLine           do something with line     You can use int Parse   or int TryParse   to convert the strings to numeric values  You may have to do some string manipulation first if there are invalid numeric characters in the strings you read

User · Answer

You can process your output synchronously or asynchronously   1  Synchronous example  static void runCommand         Process process   new Process        process StartInfo FileName    cmd exe       process StartInfo Arguments     c DIR      Note the  c command         process StartInfo UseShellExecute   false      process StartInfo RedirectStandardOutput   true      process StartInfo RedirectStandardError   true      process Start            Read the output  or the error      string output   process StandardOutput ReadToEnd        Console WriteLine output       string err   process StandardError ReadToEnd        Console WriteLine err       process WaitForExit        Note that it s better to process both output and errors  they must be handled separately       For some commands  here StartInfo Arguments  you must add the  c directive  otherwise the process freezes in the WaitForExit     2  Asynchronous example  static void runCommand              Create your Process     Process process   new Process        process StartInfo FileName    cmd exe       process StartInfo Arguments     c DIR       process StartInfo UseShellExecute   false      process StartInfo RedirectStandardOutput   true      process StartInfo RedirectStandardError   true          Set your output and error  asynchronous  handlers     process OutputDataReceived    new DataReceivedEventHandler OutputHandler       process ErrorDataReceived    new DataReceivedEventHandler OutputHandler           Start process and handlers     process Start        process BeginOutputReadLine        process BeginErrorReadLine        process WaitForExit       static void OutputHandler object sendingProcess  DataReceivedEventArgs outLine             Do your stuff with the output  write to console log StringBuilder      Console WriteLine outLine Data       If you don t need to do complicate operations with the output  you can bypass the OutputHandler method  just adding the handlers directly inline       Set your output and error  asynchronous  handlers process OutputDataReceived     s  e    gt  Console WriteLine e Data   process ErrorDataReceived     s  e    gt  Console WriteLine e Data

User · Answer

How to launch a process  such as a bat file  perl script  console program  and have its standard output displayed on a windows form   processCaller   new ProcessCaller this     processCaller FileName           hello bat   processCaller FileName     commandline exe   processCaller Arguments       processCaller StdErrReceived    new DataReceivedHandler writeStreamInfo   processCaller StdOutReceived    new DataReceivedHandler writeStreamInfo   processCaller Completed    new EventHandler processCompletedOrCanceled   processCaller Cancelled    new EventHandler processCompletedOrCanceled      processCaller Failed    no event handler for this one  yet   this richTextBox1 Text    Started function   Please stand by      Environment NewLine      the following function starts a process and returns immediately     thus allowing the form to stay responsive  processCaller Start          You can find ProcessCaller on this link  Launching a process and displaying its standard output

User · Answer

The solution that worked for me in win and linux is the folling     GET api values          HttpGet  cifrado  xml             public ActionResult lt IEnumerable lt string gt  gt  Cifrado String xml                        String nombreXML   DateTime Now ToString  ddMMyyyyhhmmss   ToString                String archivo     app files   nombreXML     XML               String comando     --armor --recipient bibankingprd bi com gt  --encrypt     archivo              try                  System IO File WriteAllText archivo  xml                                     String comando    C   GnuPG  bin  gpg exe --recipient licorera local com --armor --encrypt C   Users  Administrador  Documents  pruebas  nuevo xml                    ProcessStartInfo startInfo   new ProcessStartInfo    FileName     usr bin gpg    Arguments   comando                     Process proc   new Process     StartInfo   startInfo                     proc StartInfo RedirectStandardOutput   true                  proc StartInfo RedirectStandardError   true                  proc Start                    proc WaitForExit                    Console WriteLine proc StandardOutput ReadToEnd                     return new string      Archivo encriptado   archivo     -    comando                catch  Exception exception                   return new string     archivo   exception    exception ToString       -    comando

User · Answer

It is possible to get the command line shell output of a process as described here   http   www c-sharpcorner com UploadFile edwinlima SystemDiagnosticProcess12052005035444AM SystemDiagnosticProcess aspx  This depends on mencoder  If it ouputs this status on the command line then yes

[c#] Process.start: how to get the output?

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