mirror of https://github.com/mkerrisk/man-pages
100 lines
3.4 KiB
Groff
100 lines
3.4 KiB
Groff
.\" Copyright (c) 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)daemon.3 8.1 (Berkeley) 6/9/93
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.\" Added mentioning of glibc weirdness wrt unistd.h. 5/11/98, Al Viro
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.TH DAEMON 3 2007-07-26 "GNU" "Linux Programmer's Manual"
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.SH NAME
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daemon \- run in the background
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.SH SYNOPSIS
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.B #include <unistd.h>
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.sp
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.BI "int daemon(int " nochdir ", int " noclose );
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.BR daemon ():
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_BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE\ <\ 500)
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.SH DESCRIPTION
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The
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.BR daemon ()
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function is for programs wishing to detach themselves from the
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controlling terminal and run in the background as system daemons.
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.PP
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Unless the argument
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.I nochdir
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is non-zero,
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.BR daemon ()
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changes the current working directory to the root ("/").
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.PP
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Unless the argument
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.I noclose
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is non-zero,
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.BR daemon ()
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will redirect standard input, standard output and standard error
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to \fI/dev/null\fP.
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.SH "RETURN VALUE"
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(This function forks, and if the
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.BR fork (2)
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succeeds, the parent calls
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.\" not .IR in order not to underline _
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.BR _exit (2),
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so that further errors are seen by the child only.)
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On success zero will be returned.
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If an error occurs,
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.BR daemon ()
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returns \-1 and sets the global variable
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.I errno
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to any of the errors specified for the
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.BR fork (2)
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and
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.BR setsid (2).
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.SH CONFORMING TO
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Not in POSIX.1-2001.
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A similar function appears on the BSDs.
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The
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.BR daemon ()
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function first appeared in 4.4BSD.
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.SH NOTES
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The glibc implementation can also return \-1 when
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.I /dev/null
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exists but is not a character device with the expected
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major and minor numbers.
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In this case
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.I errno
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need not be set.
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.SH "SEE ALSO"
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.BR fork (2),
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.BR setsid (2)
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