Capturing control-key sequences

In a Linux system, how would you go about capturing Control-C (or any other control sequence)? Is it possible with C++ or would I need to make C function calls?

I found something like this for Win32, but I couldn't find anything for Linux. I'm assuming it's going to be a headache, but I'd like to see how much of a headache it will be. And no ncurses, please.

Remove windows.h, replace the call to Sleep() with a call to sleep(), and remove the final system("pause") and you should be there.

Thanks, worked like a charm.

One thing though, I compiled it in debug mode with g++, and when I went through the thing with gdb, it would not step into

Code:

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  signal( SIGINT, ctrlc_handler );

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Also, my loop was set up like this:

Code:

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  while(!ctrlc_pressed){
    std::cout << ">>> ";
    std::getline(std::cin, str_dump);
    std::cout << str_dump << std::endl;
  }

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And obviously, when I try to check what happens when I press "^C", it ends up triggering the SIGINT for gdb and not my program. So is there a way to get inside what's happening? Or do I just have to read "signal.h"?

Quote:

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Originally Posted by MSDN, via Salem

This can cause a single-thread application such as UNIX

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God, I love MSDN.


Anyway. You can't step into the signal() call because it's a system function, and there's no source for it. But it doesn't immediately call the signal handler anyway, so what do you want to step inside for?

To send a signal to the process instead of GDB, set a breakpoint, and when you're in GDB you can use one of its commands to send arbitrary signals to the debugged process. Look in the help for the exact command.

Thanks. Anyway, the wikipedia entry on signal.h helped.

Quote:

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And obviously, when I try to check what happens when I press "^C", it ends up triggering the SIGINT for gdb and not my program. So is there a way to get inside what's happening? Or do I just have to read "signal.h"?

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You can send a signal to your program with the GDB command signal. ^C is where I press CTRL-C.

Code:

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$ cat ctrlc.c
#include <stdio.h>
#include <signal.h>

static int quit = 0;

void ctrlc(int sig);

int main(void) {
    signal(SIGINT, ctrlc);

    while(!quit) {}

    puts("Exiting gracefully");
    return 0;
}

void ctrlc(int sig) {
    puts("Caught SIGINT");
    quit = 1;
}
$ gcc -g ctrlc.c -o ctrlc
$ ./ctrlc
asdf
Caught SIGINT
Exiting gracefully
$ gdb ./ctrlc
...
(gdb) run
Starting program: /home/dwk/c/ctrlc
^C
Program received signal SIGINT, Interrupt.
main () at ctrlc.c:11
11          while(!quit) {}
(gdb) signal SIGINT
Continuing with signal SIGINT.
Caught SIGINT
Exiting gracefully

Program exited normally.
(gdb) q
$

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