| DAEMON(3) | Library Functions Manual | DAEMON(3) | 
daemon —
#include <stdlib.h>
int
  
  daemon(int
    nochdir, int
    noclose);
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.
daemon() may fail and set
  errno for any of the errors specified for the library
  functions fork(2) and
  setsid(2).
daemon() function first appeared in
  4.4BSD.
daemon() will close the first three file descriptors
  and redirect them to /dev/null. Normally, these
  correspond to standard input, standard output and standard error. However, if
  any of those file descriptors refer to something else they will still be
  closed, resulting in incorrect behavior of the calling program. This can
  happen if any of standard input, standard output or standard error have been
  closed before the program was run. Programs using
  daemon() should therefore make sure to either call
  daemon() before opening any files or sockets or,
  alternately, verifying that any file descriptors obtained have a value greater
  than 2.
daemon() uses fork() as part of
  its tty detachment mechanism. Consequently the process id changes when
  daemon() is invoked. Processes employing
  daemon() can not be reliably waited upon until
  daemon() has been invoked.
| September 3, 1999 | NetBSD 9.3 |