2013-08-18 13:25:18 +00:00
|
|
|
.\" Copyright (c) 2013 Jilles Tjoelker
|
|
|
|
|
.\" All rights reserved.
|
2013-08-16 13:16:27 +00:00
|
|
|
.\"
|
|
|
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
|
|
|
.\" modification, are permitted provided that the following conditions
|
|
|
|
|
.\" are met:
|
|
|
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
|
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
|
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
|
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
|
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
|
|
|
.\"
|
2013-08-18 13:25:18 +00:00
|
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
2013-08-16 13:16:27 +00:00
|
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
|
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
2013-08-18 13:25:18 +00:00
|
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
2013-08-16 13:16:27 +00:00
|
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
|
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
|
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
|
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
|
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
|
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
|
|
|
.\" SUCH DAMAGE.
|
|
|
|
|
.\"
|
|
|
|
|
.\" $FreeBSD$
|
|
|
|
|
.\"
|
|
|
|
|
.Dd August 16, 2013
|
|
|
|
|
.Dt DUP3 3
|
|
|
|
|
.Os
|
|
|
|
|
.Sh NAME
|
|
|
|
|
.Nm dup3
|
|
|
|
|
.Nd duplicate an existing file descriptor
|
|
|
|
|
.Sh LIBRARY
|
|
|
|
|
.Lb libc
|
|
|
|
|
.Sh SYNOPSIS
|
|
|
|
|
.In fcntl.h
|
|
|
|
|
.In unistd.h
|
|
|
|
|
.Ft int
|
|
|
|
|
.Fn dup3 "int oldd" "int newd" "int flags"
|
|
|
|
|
.Sh DESCRIPTION
|
|
|
|
|
The
|
|
|
|
|
.Fn dup3
|
|
|
|
|
function
|
|
|
|
|
duplicates an existing object descriptor
|
|
|
|
|
while allowing the value of the new descriptor to be specified.
|
|
|
|
|
.Pp
|
|
|
|
|
The close-on-exec flag on the new file descriptor is determined by the
|
|
|
|
|
.Dv O_CLOEXEC
|
|
|
|
|
bit in
|
|
|
|
|
.Fa flags .
|
|
|
|
|
.Pp
|
|
|
|
|
If
|
|
|
|
|
.Fa oldd
|
|
|
|
|
\*(Ne
|
|
|
|
|
.Fa newd
|
|
|
|
|
and
|
|
|
|
|
.Fa flags
|
|
|
|
|
== 0,
|
|
|
|
|
the behavior is identical to
|
|
|
|
|
.Li dup2(oldd, newd) .
|
|
|
|
|
.Pp
|
|
|
|
|
If
|
|
|
|
|
.Fa oldd
|
|
|
|
|
==
|
|
|
|
|
.Fa newd ,
|
|
|
|
|
then
|
|
|
|
|
.Fn dup3
|
|
|
|
|
fails, unlike
|
|
|
|
|
.Xr dup2 2 .
|
|
|
|
|
.Sh RETURN VALUES
|
|
|
|
|
The value -1 is returned if an error occurs.
|
|
|
|
|
The external variable
|
|
|
|
|
.Va errno
|
|
|
|
|
indicates the cause of the error.
|
|
|
|
|
.Sh ERRORS
|
|
|
|
|
The
|
|
|
|
|
.Fn dup3
|
|
|
|
|
function fails if:
|
|
|
|
|
.Bl -tag -width Er
|
|
|
|
|
.It Bq Er EBADF
|
|
|
|
|
The
|
|
|
|
|
.Fa oldd
|
|
|
|
|
argument is not a valid active descriptor or the
|
|
|
|
|
.Fa newd
|
|
|
|
|
argument is negative or exceeds the maximum allowable descriptor number
|
|
|
|
|
.It Bq Er EINVAL
|
|
|
|
|
The
|
|
|
|
|
.Fa oldd
|
|
|
|
|
argument is equal to the
|
|
|
|
|
.Fa newd
|
|
|
|
|
argument.
|
|
|
|
|
.It Bq Er EINVAL
|
|
|
|
|
The
|
|
|
|
|
.Fa flags
|
|
|
|
|
argument has bits set other than
|
|
|
|
|
.Dv O_CLOEXEC .
|
|
|
|
|
.El
|
|
|
|
|
.Sh SEE ALSO
|
|
|
|
|
.Xr accept 2 ,
|
|
|
|
|
.Xr close 2 ,
|
|
|
|
|
.Xr dup2 2 ,
|
|
|
|
|
.Xr fcntl 2 ,
|
|
|
|
|
.Xr getdtablesize 2 ,
|
|
|
|
|
.Xr open 2 ,
|
|
|
|
|
.Xr pipe 2 ,
|
|
|
|
|
.Xr socket 2 ,
|
|
|
|
|
.Xr socketpair 2
|
|
|
|
|
.Sh STANDARDS
|
|
|
|
|
The
|
|
|
|
|
.Fn dup3
|
|
|
|
|
function does not conform to any standard.
|
|
|
|
|
.Sh HISTORY
|
|
|
|
|
The
|
|
|
|
|
.Fn dup3
|
|
|
|
|
function appeared in
|
|
|
|
|
.Fx 10.0 .
|
