kbcodes.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <linux/input.h>
#include <sys/types.h>
#include <fcntl.h>

int main (int argc, char *argv[]) {
	struct input_event ev;
	int fd = -1;
	const char *device = NULL;
	int status = 0;

	if (argc < 2) {
		fprintf(stderr, "error: no keyboard device given\n");
		goto error;
	}

	device = argv[1];
	fd = open(device, O_RDONLY);

	if (fd < 0) {
		perror(device);
		goto error;
	}

	for (;;) {
		ssize_t count = read(fd, &ev, sizeof(ev));
		if (count != sizeof(ev)) {
			perror(device);
			goto error;
		}

		if (ev.type == EV_KEY && ev.value == 1) {
			printf("%d\n", ev.code);
			fflush(stdout);
		}

	}

	goto end;

error:
	status = 1;

end:
	if (fd != -1) {
		close(fd);
	}

	return status;
}