On 12/21/05, ppunnam@xxxxxxxxxxx <ppunnam@xxxxxxxxxxx> wrote:
>
> Hi guys..
>
> I got a linux user level program, i want to make it as demon. i
> googled it but i didnt found any good tutorial ...
> if any one has some links or info please forward me.
>
Not really a kernel question, but anyway :
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <limits.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#ifdef OPEN_MAX
static int max_descriptors_open = OPEN_MAX;
#else
static int max_descriptors_open = 0;
#endif
#define MAX_TO_CLOSE 256 /* guess fallback if OPEN_MAX can't be determined */
int max_descriptors(void)
{
if (!max_descriptors_open) {
errno = 0;
max_descriptors_open = sysconf(_SC_OPEN_MAX);
if (max_descriptors_open < 0) {
if (errno == 0) {
max_descriptors_open = MAX_TO_CLOSE;
} else {
fprintf(stderr, "sysconf error _SC_OPEN_MAX: %s\n",
strerror(errno));
exit(EXIT_FAILURE);
}
}
}
return max_descriptors_open;
}
int make_me_a_daemon(void)
{
pid_t pid;
int i, nr_to_close;
if ((pid = fork()) < 0) {
/* fork failed, we can't become a daemon, errno is set */
fprintf(stderr, "fork failed while trying to daemonize: %s\n",
strerror(errno));
return -1;
} else if (pid != 0) {
exit(EXIT_SUCCESS); /* this is the parent exiting */
}
/* here we continue executing in the child */
setsid(); /* here we become session leader */
chdir("/"); /* ensure we don't keep filesystems from unmounting */
umask(0); /* make sure we can create files with any mask we like */
/* now we need to close all open filedescriptors we may have inherited.
Which ones to close depends on your daemon, so here I'll just try and
close all.
*/
nr_to_close = max_descriptors();
for (i = 0; i < nr_to_close; i++)
close(i);
/* we are now a proer daemon */
return 0;
}
int main(void)
{
printf("Trying to become a daemon\n");
if (make_me_a_daemon() != 0) {
fprintf(stderr, "Unable to become a daemon\n");
exit(EXIT_FAILURE);
}
/* Successfully became a daemon, but we can't print that fact since
we closed all file descriptors including stdout/stderr, so just
sleep for 60 seconds so we can be seen for a minute with "ps"
*/
sleep(60);
exit(EXIT_SUCCESS);
}
--
Jesper Juhl <jesper.juhl@xxxxxxxxx>
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please http://www.expita.com/nomime.html
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