1 cfa37a7b 2004-04-10 devnull .TH DUP 3
 2 cfa37a7b 2004-04-10 devnull .SH NAME
 3 cfa37a7b 2004-04-10 devnull dup \- duplicate an open file descriptor
 4 cfa37a7b 2004-04-10 devnull .SH SYNOPSIS
 5 cfa37a7b 2004-04-10 devnull .B #include <u.h>
 6 cfa37a7b 2004-04-10 devnull .br
 7 cfa37a7b 2004-04-10 devnull .B #include <libc.h>
 8 cfa37a7b 2004-04-10 devnull .PP
 9 cfa37a7b 2004-04-10 devnull .B
10 cfa37a7b 2004-04-10 devnull int dup(int oldfd, int newfd)
11 cfa37a7b 2004-04-10 devnull .SH DESCRIPTION
12 cfa37a7b 2004-04-10 devnull Given a file descriptor,
13 cfa37a7b 2004-04-10 devnull .IR oldfd ,
14 cfa37a7b 2004-04-10 devnull referring to an open file,
15 cfa37a7b 2004-04-10 devnull .I dup
16 cfa37a7b 2004-04-10 devnull returns a new file descriptor referring to the same file.
17 cfa37a7b 2004-04-10 devnull .PP
18 cfa37a7b 2004-04-10 devnull If
19 cfa37a7b 2004-04-10 devnull .I newfd
20 cfa37a7b 2004-04-10 devnull is \-1 the system chooses the lowest available file descriptor.
21 cfa37a7b 2004-04-10 devnull Otherwise,
22 cfa37a7b 2004-04-10 devnull .I dup
23 cfa37a7b 2004-04-10 devnull will use
24 cfa37a7b 2004-04-10 devnull .I newfd
25 cfa37a7b 2004-04-10 devnull for the new file descriptor
26 cfa37a7b 2004-04-10 devnull (closing any old file associated with
27 cfa37a7b 2004-04-10 devnull .IR newfd ).
28 cfa37a7b 2004-04-10 devnull .SH SOURCE
29 c3674de4 2005-01-11 devnull .B \*9/src/lib9/dup.c
30 cfa37a7b 2004-04-10 devnull .SH DIAGNOSTICS
31 cfa37a7b 2004-04-10 devnull Sets
32 cfa37a7b 2004-04-10 devnull .IR errstr .
33 058b0118 2005-01-03 devnull .SH BUGS
34 c8b6342d 2005-01-13 devnull To avoid name conflicts with the underlying system,
35 c8b6342d 2005-01-13 devnull .I dup
36 c8b6342d 2005-01-13 devnull is a preprocessor macro defined as
37 c8b6342d 2005-01-13 devnull .IR p9dup ;
38 c8b6342d 2005-01-13 devnull see
39 d32deab1 2020-08-16 rsc .MR intro (3) .