Execute a command after some time of inactivity

sleepd.c

/*
 * Execute a command after some time of inactivity
 *
 * Compile:
 * $ cc -o sleepd sleepd.c
 *
 * Usage:
 * $ ./sleepd -t 600 -c "slock"
 *
 * NOTE: to run this as a normal (non-root) user you may need to change
 * /dev/input/event* devices permissions, e.g. using udev:
 *
 *   KERNEL=="event*", NAME="input/%k", MODE="644", GROUP="input"
 *
 * then create the group "input" and add your user to it. Be aware that this
 * may have security implications, particularly on shared boxes.
 *
 * Copyright (C) 2012 Alessandro Ghedini <alessandro@ghedini.me>
 * --------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * Alessandro Ghedini wrote this file. As long as you retain this
 * notice you can do whatever you want with this stuff. If we
 * meet some day, and you think this stuff is worth it, you can
 * buy me a beer in return.
 * --------------------------------------------------------------
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <fcntl.h>
#include <getopt.h>
#include <unistd.h>

#include <sys/select.h>
#include <sys/types.h>

fd_set ev;
int devs[128];

void init_ev() {
	int i = 0;

	FD_ZERO(&ev);

	do {
		int fd;
		char dev_name[128];

		snprintf(dev_name, 127, "/dev/input/event%d", i++);
		fd = open(dev_name, O_RDONLY);

		if (fd < 0) break;

		devs[i] = fd;
		FD_SET(fd, &ev);
	} while (1);
}

void clean_ev() {
	int i;

	for (i = 0; i < 128; i++)
		close(devs[i]);
}

void usage(char *name) {
	fprintf(stderr, "Usage: %s -t <timeout> -c <command>\n", name);
	exit(-1);
}

int main(int argc, char *argv[]) {
	char *cmd = NULL;
	int opt, timeout = 0, enabled = 1;

	struct timeval tv;

	while ((opt = getopt(argc, argv, "c:t:")) != -1) {
		switch (opt) {
			case 'c':
				cmd = strdup(optarg);
				break;
			case 't':
				timeout = atoi(optarg);
				break;
			default:
				usage(argv[0]);
		}
	}

	if ((timeout == 0) || (cmd == NULL))
		usage(argv[0]);

	while (1) {
		int rc;

		init_ev();

		tv.tv_sec  = timeout;
		tv.tv_usec = 0;

		rc = select(FD_SETSIZE, &ev, NULL, NULL, &tv);

		switch (rc) {
			case -1: {
				perror("sleepd");
				return -1;
			}

			case  0: {
				if (enabled) {
					enabled = 0;
					system(cmd);
				}

				break;
			}

			default: {
				enabled = 1;
				break;
			}
		}

		clean_ev();
	}

	return 0;
}

I was looking for how to do exactly this. Muchas Gracias!

[EDIT] using xterm and putting sleepd into background, it starts after delay, regardless of term activity.

I want to only trigger my program if I am idle on keyboard > X seconds.

./sleepd -t 6 -c "./oldthugs"&

Any ideas how to do this?