.TH DUP 2
.SH NAME
dup \- duplicate an open file descriptor
.SH SYNOPSIS
.B
int dup(int oldfd, int newfd)
.SH DESCRIPTION
Given a file descriptor,
.IR oldfd ,
referring to an open file,
.I dup
returns a new file descriptor referring to the same file.
If
.I newfd
is in the range of legal file descriptors
.I dup
will use that for the new file descriptor
(closing any old file associated with
.IR newfd);
if
.I newfd
is \-1 the system chooses the lowest available file descriptor.
.SH SEE ALSO
.IR intro (2),
.IR dup (3)
.SH DIAGNOSTICS
Sets
.I errstr.