daemon(3) [netbsd man page]

DAEMON(3)						   BSD Library Functions Manual 						 DAEMON(3)

NAME

     daemon -- run in the background

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <stdlib.h>

     int
     daemon(int nochdir, int noclose);

DESCRIPTION

     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.

RETURN VALUES

     On return 0 indicates success with -1 indicating error.

ERRORS

     The function daemon() may fail and set errno for any of the errors specified for the library functions fork(2) and setsid(2).

SEE ALSO

     fork(2), setsid(2)

HISTORY

     The daemon() function first appeared in 4.4BSD.

CAVEATS

     Unless the noclose argument is non-zero, 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.

BUGS

     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.

BSD
								 September 3, 1999							       BSD

DAEMON(3)						   BSD Library Functions Manual 						 DAEMON(3)

NAME

     daemon -- run in the background

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <stdlib.h>

     int
     daemon(int nochdir, int noclose);

DESCRIPTION

     The daemon() function is for programs wishing to detach themselves from the controlling terminal and run in the background as system daemons.
     On Mac OS X, the use of this API is discouraged in favor of using launchd(8).

     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.

RETURN VALUES

     The daemon() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate
     the error.

ERRORS

     The daemon() function may fail and set errno for any of the errors specified for the library functions fork(2) and setsid(2).

SEE ALSO

     fork(2), setsid(2), sigaction(2)

HISTORY

     The daemon() function first appeared in 4.4BSD.

CAVEATS

     Unless the noclose argument is non-zero, 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 out-
     put, or standard error have been closed before the program was run.  Programs using daemon() should therefore either call daemon() before
     opening any files or sockets, or verify that any file descriptors obtained have values greater than 2.

     The daemon() function temporarily ignores SIGHUP while calling setsid(2) to prevent a parent session group leader's calls to fork(2) and then
     _exit(2) from prematurely terminating the child process.

BSD
								   June 9, 1993 							       BSD