How to catch an interrupt (Control-C) in a script?

Question

If a user hits Control-C when a script is running, they get an Interrupt> prompt, where they have to type exit or quit to return to the shell. I'd like to have the interpreter exit immediately when Control-C is hit. To this end, I'd like to catch the interrupt and run Exit. Is there a way to do this? Or is there a better option?

Answer 1

Here's an ugly hack that works, based directly on this answer. This doesn't work on Windows.

First create a LibraryLink function that can set an alternate signal handler:

<< CCompilerDriver`

handlerlib = "
  #include <signal.h>
  #include <stdlib.h>
  #include <stdio.h>

  #include \"WolframLibrary.h\"

  // you may want to specialize this for SIGINT only
  void my_handler(int s){
             printf(\"Caught signal %d\\n\",s);
             exit(1); 
  }

  DLLEXPORT mint WolframLibrary_getVersion(){
    return WolframLibraryVersion;
  }

  DLLEXPORT int WolframLibrary_initialize( WolframLibraryData libData) {
      return 0;
  }

  DLLEXPORT void WolframLibrary_uninitialize( WolframLibraryData libData) {
    return;
  }

  DLLEXPORT void setHandler(WolframLibraryData libData, mint Argc, MArgument *Args, MArgument Res) {
     struct sigaction sigIntHandler;

     sigIntHandler.sa_handler = my_handler;
     sigemptyset(&sigIntHandler.sa_mask);
     sigIntHandler.sa_flags = 0;

     sigaction(SIGINT, &sigIntHandler, NULL);

     return LIBRARY_NO_ERROR;
  }
  ";

CreateLibrary[handlerlib, "handlerlib"]

Once the library is compiled, you can use it in any Mathematica session on the same machine.

So just put this at the beginning of your script:

LibraryFunctionLoad["handlerlib", "setHandler", {}, "Void"][]

Now Ctrl-C will kill the script immediately.

You could suggest to support that this be the default behaviour when Mathematica is invoked using the -script option.