Manual Pages for UNIX Operating System command usage for man daemon

Standard C Library Functions                           daemon(3C)



NAME
     daemon - basic daemonization function

SYNOPSIS
     #include 

     int daemon(int nochdir, int noclose);


DESCRIPTION
     The daemon() function provides a means for  applications  to
     run in the background.


     This function ensures that the process  calling  this  func-
     tion:

         o    runs in the background

         o    detaches from the controlling terminal

         o    forms a new process group

         o    is not a session group leader.


     The arguments to this function are treated as boolean  vari-
     ables and are evaluated using negative logic.


     If the nochdir argument is zero the working  directory  will
     be  changed to the root directory (/); otherwise it will not
     be.


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

RETURN VALUES
     Upon successful completion, daemon() returns 0. Otherwise it
     returns  -1  and  sets  errno  to  the  values specified for
     fork(2), setsid(2), open(2), and dup(2).


     If daemon() is called with noclose set to  0  and  fails  to
     redirect  descriptors  0,  1,  and  2  to  /dev/null,  those
     descriptors are not guaranteed to be the same as before  the
     call.





SunOS 5.11          Last change: 15 Sep 2009                    1






Standard C Library Functions                           daemon(3C)



EXAMPLES
     Example 1 Using daemon to run a process in the background.


     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
     Intro(2), dup(2), fork(2), open(2), setsid(2), attributes(5)



















SunOS 5.11          Last change: 15 Sep 2009                    2