Manual page for dup(2)
dup - duplicate an open file descriptor
SYNOPSIS
#include <unistd.h>
int dup(int fildes);
DESCRIPTION
dup()
returns a new
file descriptor
having the following in common with the original open file descriptor
fildes:
Same open file (or pipe).
Same file pointer
(that is, both file descriptors share one file pointer).
Same access mode (read, write or read/write).
The new
file descriptor
is set to remain open across
exec
functions
(see
fcntl.2
The
file descriptor
returned is the lowest one available.
The
dup(fildes)
is equivalent to
-
fcntl( fildes, F_DUPFD, 0 )
RETURN VALUES
Upon successful completion a non-negative integer,
namely the file descriptor, is returned.
Otherwise, a value of -1 is returned and
errno is set to indicate the error.
ERRORS
dup()
will fail if one or more of the following are true:
- EBADF
-
fildes
is not a valid open
file descriptor.
- EINTR
-
A signal was caught during the
dup()
function.
- EMFILE
-
The process has too many open files (see
getrlimit.2
- ENOLINK
-
fildes is on a remote machine and the link
to that machine is no longer active.
ATTRIBUTES
See
attributes.5
for descriptions of the following attributes:
+---------------+-------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-------------------+
|MT-Level | Async-Signal-Safe |
+---------------+-------------------+
SEE ALSO
close.2
creat.2
exec.2
fcntl.2
getrlimit.2
open.2
pipe.2
dup2.3c
lockf.3c
attributes.5
Created by unroff & hp-tools.
© by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 07/October/97
