Can I send a ctrl-C SIGINT to an application on Windows

Question

I have  in the past  written cross-platform  Windows Unix  applications which  when started from the command line  handled a user-typed Ctrl-C combination in the same way  i e  to terminate the application cleanly    Is it possible on Windows to send a Ctrl-C SIGINT equivalent to a process from another  unrelated  process to request that it terminate cleanly  giving it an opportunity to tidy up resources etc

User · Answer

A friend of mine suggested a complete different way of solving the problem and it worked for me. Use a vbscript like below. It starts and application, let it run for 7 seconds and close it using ctrl+c.

'VBScript Example

Set WshShell = WScript.CreateObject("WScript.Shell")

WshShell.Run "notepad.exe"

WshShell.AppActivate "notepad"

WScript.Sleep 7000

WshShell.SendKeys "^C"

User · Answer

Edit   For a GUI App  the  normal  way to handle this in Windows development would be to send a WM CLOSE message to the process s main window   For a console app  you need to use SetConsoleCtrlHandler to add a CTRL C EVENT   If the application doesn t honor that  you could call TerminateProcess

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Thanks to jimhark s answer and other answers here  I found a way to do it in PowerShell   ProcessID   1234  MemberDefinition          DllImport  quot kernel32 dll quot   public static extern bool FreeConsole         DllImport  quot kernel32 dll quot   public static extern bool AttachConsole uint p        DllImport  quot kernel32 dll quot   public static extern bool GenerateConsoleCtrlEvent uint e  uint p       public static void SendCtrlC uint p            FreeConsole            if  AttachConsole p                 GenerateConsoleCtrlEvent 0  p               FreeConsole                      AttachConsole uint MaxValue          Add-Type -Name  dummyName  -Namespace  dummyNamespace  -MemberDefinition  MemberDefinition  dummyNamespace dummyName   SendCtrlC  ProcessID      What made things work was sending the GenerateConsoleCtrlEvent to the desired process group instead of all processes that share the console of the calling process and AttachConsole back to the console of the parent of the current process

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Here is the code I use in my C   app   Positive points     Works from console app Works from Windows service No delay required Does not close the current app   Negative points     The main console is lost and a new one is created  see FreeConsole  The console switching give strange results           Inspired from http   stackoverflow com a 15281070 1529139    and http   stackoverflow com q 40059902 1529139 bool signalCtrl DWORD dwProcessId  DWORD dwCtrlEvent        bool success   false      DWORD thisConsoleId   GetCurrentProcessId           Leave current console if it exists         otherwise AttachConsole will return ERROR ACCESS DENIED      bool consoleDetached    FreeConsole      FALSE        if  AttachConsole dwProcessId     FALSE                   Add a fake Ctrl-C handler for avoid instant kill is this console            WARNING  do not revert it or current program will be also killed         SetConsoleCtrlHandler nullptr  true           success    GenerateConsoleCtrlEvent dwCtrlEvent  0     FALSE           FreeConsole               if  consoleDetached                   Create a new console if previous was deleted by OS         if  AttachConsole thisConsoleId     FALSE                        int errorCode   GetLastError                if  errorCode    31     31 ERROR GEN FAILURE                               AllocConsole                                      return success      Usage example    DWORD dwProcessId        if  signalCtrl dwProcessId  CTRL C EVENT         cout  lt  lt   Signal sent   lt  lt  endl

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It should be made crystal clear because at the moment it isn t   There is a modified and compiled version of SendSignal to send Ctrl-C  by default it only sends Ctrl Break   Here are some binaries       2014-3-7    I built both 32-bit and 64-bit version with Ctrl-C  it s called SendSignalCtrlC exe and you can download it at  https   dl dropboxusercontent com u 49065779 sendsignalctrlc x86 SendSignalCtrlC exe https   dl dropboxusercontent com u 49065779 sendsignalctrlc x86 64 SendSignalCtrlC exe -- Juraj Michalak    I have also mirrored those files just in case  32-bit version  https   www dropbox com s r96jxglhkm4sjz2 SendSignalCtrlC exe dl 0  64-bit version  https   www dropbox com s hhe0io7mcgcle1c SendSignalCtrlC64 exe dl 0  Disclaimer  I didn t build those files  No modification was made to the compiled original files  The only platform tested is the 64-bit Windows 7  It is recommended to adapt the source available at http   www latenighthacking com projects 2003 sendSignal  and compile it yourself

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I have done some research around this topic  which turned out to be more popular than I anticipated  KindDragon s reply was one of the pivotal points   I wrote a longer blog post on the topic and created a working demo program  which demonstrates using this type of system to close a command line application in a couple of nice fashions  That post also lists external links that I used in my research   In short  those demo programs do the following    Start a program with a visible window using  Net  hide with pinvoke  run for 6 seconds  show with pinvoke  stop with  Net  Start a program without a window using  Net  run for 6 seconds  stop by attaching console and issuing ConsoleCtrlEvent   Edit  The amended solution from KindDragon for those who are interested in the code here and now  If you plan to start other programs after stopping the first one  you should re-enable Ctrl-C handling  otherwise the next process will inherit the parent s disabled state and will not respond to Ctrl-C    DllImport  kernel32 dll   SetLastError   true   static extern bool AttachConsole uint dwProcessId     DllImport  kernel32 dll   SetLastError   true  ExactSpelling   true   static extern bool FreeConsole      DllImport  kernel32 dll    static extern bool SetConsoleCtrlHandler ConsoleCtrlDelegate HandlerRoutine  bool Add    delegate bool ConsoleCtrlDelegate CtrlTypes CtrlType       Enumerated type for the control messages sent to the handler routine enum CtrlTypes   uint     CTRL C EVENT   0    CTRL BREAK EVENT    CTRL CLOSE EVENT    CTRL LOGOFF EVENT   5    CTRL SHUTDOWN EVENT     DllImport  kernel32 dll     return  MarshalAs UnmanagedType Bool   private static extern bool GenerateConsoleCtrlEvent CtrlTypes dwCtrlEvent  uint dwProcessGroupId    public void StopProgram Process proc        This does not require the console window to be visible    if  AttachConsole  uint proc Id              Disable Ctrl-C handling for our program     SetConsoleCtrlHandler null  true        GenerateConsoleCtrlEvent CtrlTypes CTRL C EVENT  0          Moved this command up on suggestion from Timothy Jannace  see comments below      FreeConsole            Must wait here  If we don t and re-enable Ctrl-C        handling below too fast  we might terminate ourselves      proc WaitForExit 2000          Re-enable Ctrl-C handling or any subsequently started       programs will inherit the disabled state      SetConsoleCtrlHandler null  false            Also  plan for a contingency solution if AttachConsole   or the sent signal should fail  for instance sleeping then this   if   proc HasExited      try         proc Kill          catch  InvalidOperationException e

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Somehow GenerateConsoleCtrlEvent   return error if you call it for another process  but you can attach to another console application and send event to all child processes   void SendControlC int pid        AttachConsole pid      attach to process console     SetConsoleCtrlHandler NULL  TRUE      disable Control C handling for our app     GenerateConsoleCtrlEvent CTRL C EVENT  0      generate Control C event

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Based on process id  we can send the signal to process to terminate forcefully or gracefully or any other signal   List all process     C   gt tasklist   To kill the process   C   gt Taskkill  IM firefox exe  F or C   gt Taskkill  PID 26356  F   Details   http   tweaks com windows 39559 kill-processes-from-command-prompt

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Yes  The windows-kill project does exactly what you want   windows-kill -SIGINT 1234

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In Java  using JNA with the Kernel32 dll library  similar to a C   solution  Runs the CtrlCSender main method as a Process which just gets the console of the process to send the Ctrl C event to and generates the event  As it runs separately without a console the Ctrl C event does not need to be disabled and enabled again   CtrlCSender java - Based on Nemo1024 s  and KindDragon s  answers   Given a known process ID  this consoless application will attach the console of targeted process and generate a CTRL C Event on it   import com sun jna platform win32 Kernel32       public class CtrlCSender        public static void main String args              int processId   Integer parseInt args 0            Kernel32 INSTANCE AttachConsole processId           Kernel32 INSTANCE GenerateConsoleCtrlEvent Kernel32 CTRL C EVENT  0             Main Application - Runs CtrlCSender as a separate consoless process  ProcessBuilder pb   new ProcessBuilder    pb command  javaw    -cp   System getProperty  java class path         CtrlCSender class getName    processId   pb redirectErrorStream    pb redirectOutput ProcessBuilder Redirect INHERIT   pb redirectError ProcessBuilder Redirect INHERIT   Process ctrlCProcess   pb start    ctrlCProcess waitFor

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I found all this too complicated and used SendKeys to send a CTRL-C keystroke to the command line window  i e  cmd exe window  as a workaround

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Send  CTRL-C  to interrupt a batch file running in a Command Prompt window  even if the Command Prompt window is not visible     without bringing the Command Prompt window into focus      CTRL-C  will have an effect on the batch file  but not on the Command Prompt  window itself -- in other words      CTRL-C  will not have the same visible effect on a Command Prompt window that isn t running a batch file at the moment    as bringing a Command Prompt window that isn t running a batch file into focus and pressing  CTRL-C  on the keyboard  ulong ulProcessId   0UL     hwC   Find Command Prompt window HWND GetWindowThreadProcessId  hwC   LPDWORD   amp ulProcessId   AttachConsole   DWORD  ulProcessId   SetConsoleCtrlHandler  NULL  TRUE   GenerateConsoleCtrlEvent  CTRL C EVENT  0UL   SetConsoleCtrlHandler  NULL  FALSE   FreeConsole

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void SendSIGINT  HANDLE hProcess                         DWORD pid   GetProcessId hProcess               FreeConsole                if  AttachConsole pid                                    Disable Ctrl-C handling for our program                 SetConsoleCtrlHandler NULL  true                    GenerateConsoleCtrlEvent CTRL C EVENT  0      SIGINT                    Re-enable Ctrl-C handling or any subsequently started                   programs will inherit the disabled state                  SetConsoleCtrlHandler NULL  false                    WaitForSingleObject hProcess  10000

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A solution that I have found from here is pretty simple if you have python 3 x available in your command line   First  save a file  ctrl c py  with the contents  import ctypes import sys  kernel   ctypes windll kernel32  pid   int sys argv 1   kernel FreeConsole   kernel AttachConsole pid  kernel SetConsoleCtrlHandler None  1  kernel GenerateConsoleCtrlEvent 0  0  sys exit 0   Then call  python ctrl c py 12345  If that doesn t work  I recommend trying out the windows-kill project  https   github com alirdn windows-kill

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The closest that I ve come to a solution is the SendSignal 3rd party app   The author lists source code and an executable   I ve verified that it works under 64-bit windows  running as a 32-bit program  killing another 32-bit program   but I ve not figured out how to embed the code into a windows program  either 32-bit or 64-bit   How it works   After much digging around in the debugger I discovered that the entry point that actually does the behavior associated with a signal like ctrl-break is kernel32 CtrlRoutine  The function had the same prototype as ThreadProc  so it can be used with CreateRemoteThread directly  without having to inject code  However  that s not an exported symbol  It s at different addresses  and even has different names  on different versions of Windows  What to do  Here is the solution I finally came up with  I install a console ctrl handler for my app  then generate a ctrl-break signal for my app  When my handler gets called  I look back at the top of the stack to find out the parameters passed to kernel32 BaseThreadStart  I grab the first param  which is the desired start address of the thread  which is the address of kernel32 CtrlRoutine  Then I return from my handler  indicating that I have handled the signal and my app should not be terminated  Back in the main thread  I wait until the address of kernel32 CtrlRoutine has been retrieved  Once I ve got it  I create a remote thread in the target process with the discovered start address  This causes the ctrl handlers in the target process to be evaluated as if ctrl-break had been pressed  The nice thing is that only the target process is affected  and any process  even a windowed process  can be targeted  One downside is that my little app can t be used in a batch file  since it will kill it when it sends the ctrl-break event in order to discover the address of kernel32 CtrlRoutine    Precede it with start if running it in a batch file

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SIGINT can be send to program using windows-kill  by syntax windows-kill -SIGINT PID  where PID can be obtained by Microsoft s pslist  Regarding catching SIGINTs  if your program is in Python then you can implement SIGINT processing catching like in this solution

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I guess I m a bit late on this question but I ll write something anyway for anyone having the same problem  This is the same answer as I gave to this question   My problem was that I d like my application to be a GUI application but the processes executed should be run in the background without any interactive console window attached  I think this solution should also work when the parent process is a console process  You may have to remove the  CREATE NO WINDOW  flag though   I managed to solve this using GenerateConsoleCtrlEvent   with a wrapper app  The tricky part is just that the documentation is not really clear on exactly how it can be used and the pitfalls with it   My solution is based on what is described here  But that didn t really explain all the details either and with an error  so here is the details on how to get it working   Create a new helper application  Helper exe   This application will sit between your application  parent  and the child process you want to be able to close  It will also create the actual child process  You must have this  middle man  process or GenerateConsoleCtrlEvent   will fail   Use some kind of IPC mechanism to communicate from the parent to the helper process that the helper should close the child process  When the helper get this event it calls  GenerateConsoleCtrlEvent CTRL BREAK  0   which closes down itself and the child process  I used an event object for this myself which the parent completes when it wants to cancel the child process   To create your Helper exe create it with CREATE NO WINDOW and CREATE NEW PROCESS GROUP  And when creating the child process create it with no flags  0  meaning it will derive the console from its parent  Failing to do this will cause it to ignore the event   It is very important that each step is done like this  I ve been trying all different kinds of combinations but this combination is the only one that works  You can t send a CTRL C event  It will return success but will be ignored by the process  CTRL BREAK is the only one that works  Doesn t really matter since they will both call ExitProcess   in the end   You also can t call GenerateConsoleCtrlEvent   with a process groupd id of the child process id directly allowing the helper process to continue living  This will fail as well   I spent a whole day trying to get this working  This solution works for me but if anyone has anything else to add please do  I went all over the net finding lots of people with similar problems but no definite solution to the problem  How GenerateConsoleCtrlEvent   works is also a bit weird so if anyone knows more details on it please share

[windows] Can I send a ctrl-C (SIGINT) to an application on Windows?

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