Manual Pages  — DAEMON

daemon – run in the background

LIBRARY SYNOPSIS DESCRIPTION RETURN VALUES ERRORS SEE ALSO HISTORY CAVEATS

Standard C Library (libc, -lc)

#include <stdlib.h>

int
daemon(int nochdir, int noclose);

int
daemonfd(int chdirfd, int nullfd);

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

If the argument nochdir is zero, daemon() changes the current working directory to the root ( /).

If the argument noclose is zero, daemon() redirects standard input, standard output, and standard error to /dev/null.

The daemonfd() function is equivalent to the daemon() function except that arguments are the descriptors for the current working directory and to the descriptor to /dev/null.

If chdirfd is equal to (-1) the current working directory is not changed.

If nullfd is equals to (-1) the redirection of standard input, standard output, and standard error is not closed.

The daemonand daemonfd functions return the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

The daemon() function first appeared in BSD 4.4 . The daemonfd() function first appeared in FreeBSD 12.0 .