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NAME    [Toc]    [Back]

     daemon - run in the background

SYNOPSIS    [Toc]    [Back]

     #include <stdlib.h>

     daemon(int nochdir, int noclose);

DESCRIPTION    [Toc]    [Back]

     The daemon() function is  for  programs  wishing  to  detach
themselves from
     the controlling terminal and run in the background as system

     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    [Toc]    [Back]

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

ERRORS    [Toc]    [Back]

     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    [Toc]    [Back]

     fork(2), setsid(2)

HISTORY    [Toc]    [Back]

     The daemon() function first appeared in 4.4BSD.

CAVEATS    [Toc]    [Back]

     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.

OpenBSD      3.6                           June      9,      1993
[ Back ]
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