daemon − run in the background

#include <unistd.h>

int daemon(int nochdir, int noclose);

The daemon() function is for programs wishing to detach themselves from the controlling terminal and run in the background as system daemons.

Unless the argument nochdir is non-zero, daemon() changes the current working directory to the root ("/").

Unless the argument noclose is non-zero, daemon() will redirect standard input, standard output and standard error to /dev/null.

(This function forks, and if the fork() succeeds, the parent does _exit(0), so that further errors are seen by the child only.) On success zero will be returned. If an error occurs, daemon() returns −1 and sets the global variable errno to any of the errors specified for the library functions fork(2) and setsid(2).

fork(2), setsid(2)

The glibc implementation can also return −1 when /dev/null exists but is not a character device with the expected major and minor numbers. In this case errno need not be set.

The daemon() function first appeared in BSD4.4.