Standard C Library Functions                              daemon(3C)



NAME
     daemon - basic daemonization function

SYNOPSIS
     #include <stdlib.h>

     int daemon(int nochdir, int noclose);


DESCRIPTION
     The daemon() function provides a way for applications to go into
     background.

     The function will ensure that the process calling this function:
       - runs in the background
       - detaches from the controlling terminal
       - forms a new process group
       - is not a session group leader

     The options to the function are treated as boolean variables and are
     evaluated using negative logic.

     If the nochdir option is other than zero the working directory will
     not be changed to the root directory ("/"), otherwise it will be.

     If the noclose option is other than zero the descriptors 0,1,2
     (normally corresponding to standard input, output and error output,
     depending on the application) will not be redirected to /dev/null,
     otherwise they will be.

RETURN VALUES
     Upon successful completion, daemon() returns 0. Otherwise it returns -1
     in which case errno will be set to the values specified in fork(2) and
     setsid(2).

EXAMPLES

     The main() function of a network server could look like this:

     int background;	/* background flag */

     /* Load and verify the configuration. */

     /* Go into background. */
     if (background && daemon(0, 0) < 0)
             err(1, "daemon");

     /* Process requests here. */

ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    | Async-Signal-Safe           |
    |_____________________________|_____________________________|


SEE ALSO
     attributes(5), fork(2), Intro(2), setsid(2)