MirOS Manual: daemon(3)

DAEMON(3)                  BSD Programmer's Manual                   DAEMON(3)

NAME

     daemon - run in the background

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

     Upon success, daemon() returns 0; otherwise -1 is returned.

ERRORS

     The function daemon() may fail and set errno for any of the errors speci-
     fied 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. Howev-
     er, 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 er-
     ror 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 ob-
     tained have a value greater than 2.

MirOS BSD #10-current            June 9, 1993                                1

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