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28 .\" @(#)daemon.3 8.1 (Berkeley) 6/9/93
35 .Nd run in the background
41 .Fn daemon "int nochdir" "int noclose"
43 .Fn daemonfd "int chdirfd" "int nullfd"
47 function is for programs wishing to detach themselves from the
48 controlling terminal and run in the background as system daemons.
54 changes the current working directory to the root
61 redirects standard input, standard output, and standard error to
66 function is equivalent to the
68 function except that arguments are the descriptors for the current working
69 directory and to the descriptor to
76 the current working directory is not changed.
82 the redirection of standard input, standard output, and standard error is not
85 .Rv -std daemon daemonfd
91 function may fail and set
93 for any of the errors specified for the library functions
105 function first appeared in
109 function first appeared in
114 argument is non-zero,
116 will close the first three file descriptors and redirect them to
118 Normally, these correspond to standard input, standard output, and
120 However, if any of those file descriptors refer to something else, they
121 will still be closed, resulting in incorrect behavior of the calling program.
122 This can happen if any of standard input, standard output, or standard
123 error have been closed before the program was run.
126 should therefore either call
128 before opening any files or sockets, or verify that any file
129 descriptors obtained have values greater than 2.
133 function temporarily ignores
137 to prevent a parent session group leader's calls to
141 from prematurely terminating the child process.