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.

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.

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 .