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



NAME
       daemon - run in the background

SYNOPSIS
       #include <unistd.h>

       int daemon(int nochdir, int noclose);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       daemon(): _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)

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

       If nochdir is zero, daemon() changes the calling process's current  working  directory  to
       the root directory ("/"); otherwise, the current working directory is left unchanged.

       If  noclose is zero, daemon() redirects standard input, standard output and standard error
       to /dev/null; otherwise, no changes are made to these file descriptors.

RETURN VALUE
       (This function forks, and if the fork(2) succeeds, the parent calls _exit(2), so that fur‐
       ther  errors  are seen by the child only.)  On success daemon() returns zero.  If an error
       occurs, daemon() returns -1 and sets errno to any of the errors specified for the  fork(2)
       and setsid(2).

ATTRIBUTES
   Multithreading (see pthreads(7))
       The daemon() function is thread-safe.

CONFORMING TO
       Not in POSIX.1-2001.  A similar function appears on the BSDs.  The daemon() function first
       appeared in 4.4BSD.

NOTES
       The glibc implementation can also return -1 when /dev/null exists but is not  a  character
       device with the expected major and minor numbers.  In this case, errno need not be set.

SEE ALSO
       fork(2), setsid(2)

COLOPHON
       This  page  is  part of release 3.74 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at http://www.kernel.org/doc/man-pages/.



GNU                                         2013-10-28                                  DAEMON(3)