DUP(2)DUP(2)
NAME
dup – duplicate an open file descriptor
SYNOPSIS
#include <u.h>
#include <libc.h>
int dup(int oldfd, int newfd)
DESCRIPTION
Given a file descriptor,
oldfd,
referring to an open file,
dup
returns a new file descriptor referring to the same file.
If
newfd
is –1 the system chooses the lowest available file descriptor.
Otherwise,
dup
will use
newfd
for the new file descriptor
(closing any old file associated with
newfd).
File descriptors are allocated dynamically,
so to prevent unwarranted growth of the file descriptor table,
dup
requires that
newfd
be no greater than 20 more than the highest file descriptor ever used by
the program.
SOURCE
/sys/src/libc/9syscall
SEE
intro(2),
dup(3)
DIAGNOSTICS
Sets
errstr.