minix/lib/libc/gen/daemon.3
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

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Groff

.\" $NetBSD: daemon.3,v 1.15 2003/08/07 16:42:46 agc Exp $
.\"
.\" Copyright (c) 1993
.\" The Regents of the University of California. All rights reserved.
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.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" SUCH DAMAGE.
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.\" @(#)daemon.3 8.1 (Berkeley) 6/9/93
.\"
.Dd September 3, 1999
.Dt DAEMON 3
.Os
.Sh NAME
.Nm daemon
.Nd run in the background
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft int
.Fn daemon "int nochdir" "int noclose"
.Sh DESCRIPTION
The
.Fn daemon
function is for programs wishing to detach themselves from the
controlling terminal and run in the background as system daemons.
.Pp
Unless the argument
.Fa nochdir
is non-zero,
.Fn daemon
changes the current working directory to the root
.Pq Pa / .
.Pp
Unless the argument
.Fa noclose
is non-zero,
.Fn daemon
will redirect standard input, standard output and standard error
to
.Pa /dev/null .
.Sh RETURN VALUES
On return 0 indicates success with \-1 indicating error.
.Sh ERRORS
The function
.Fn daemon
may fail and set
.Va errno
for any of the errors specified for the library functions
.Xr fork 2
and
.Xr setsid 2 .
.Sh SEE ALSO
.Xr fork 2 ,
.Xr setsid 2
.Sh HISTORY
The
.Fn daemon
function first appeared in
.Bx 4.4 .
.Sh CAVEATS
Unless the
.Ar noclose
argument is non-zero,
.Fn daemon
will close the first three file descriptors and redirect them to
.Pa /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
.Fn daemon
should therefore make sure to either call
.Fn daemon
before opening any files or sockets or, alternately, verifying that
any file descriptors obtained have a value greater than 2.
.Sh BUGS
.Fn daemon
uses
.Fn fork
as part of its tty detachment mechanism.
Consequently the process id changes when
.Fn daemon
is invoked.
Processes employing
.Fn daemon
can not be reliably waited upon until
.Fn daemon
has been invoked.