Beep on Linux in C

Question

I want to generate a beep sound with a specific frequency and length (for different sound signals) using the system beeper (and only the speakers if beeper is not available / accessible). I know it is possible to do this by using ioctl, but that requires root access, which I don't want.

I know I could just use the "beep" command, but that would be a dependency, which, if possible, shouldn't be used (no external dependencies at all, just the basic linux libraries and C).

What I currently have is the following code (but this requires superuser privileges to run):

#include <stdlib.h>
#include <fcntl.h>
#include <linux/kd.h>

int main(int argc, char *argv[])
{
 int fd = open("/dev/console", O_RDONLY);
 if (fd == -1 || argc != 3) return -1;
 return ioctl(fd, KDMKTONE, (atoi(argv[2])<<16)+(1193180/atoi(argv[1])));
}

If there is no other way to do this, then I will use beep, but I would really like to avoid dependencies and integrate the beep directly into my script, but I'm sure somebody here will know a solution / workaround.

I don't really want external libraries as the program should be as lightweight as possible.

Answer 1

Please look at the standard linux beep source code. http://www.johnath.com/beep/beep.c

It uses KIOCSOUND ioctl to "beep", but you don't need superuser privileges to make it play. I have configured it to be readable and executable by users on the "beep" group.

So my standard user with UID 1000 is in the group with GID 501 (i called it "beep"). Next to this I had to chmod 4750 /usr/bin/beep and now I'm able to play beeps (in the range 20-20000Hz) without asking for superuser privileges.