dup.2 (2010 09)

d
dup(2) dup(2)
NAME
dup - duplicate an open file descriptor
SYNOPSIS
#include <unistd.h>
int dup(int fildes);
DESCRIPTION
fildes is a file descriptor obtained from a
creat(), open(), dup(), fcntl(),or pipe() system call.
dup() returns a new file descriptor having the following in common with the original:
• Same open file (or pipe).
• Same file pointer (i.e., both file descriptors share one file pointer).
• Same access mode (read, write or read/write).
• Same file status flags (see fcntl (2),
F_DUPFD).
The new file descriptor is set to remain open across
exec() system calls. See fcntl (2).
The file descriptor returned is the lowest one available.
RETURN VALUE
Upon successful completion, the file descriptor is returned as a non-negative integer. Otherwise, a value
of −1 is returned and
errno is set to indicate the error.
ERRORS
dup() fails if one or more of the following is true:
[EBADF] fildes is not a valid open file descriptor.
[EMFILE] Request violates the maximum number of open file descriptors.
AUTHOR
dup() was developed by AT&T and HP.
SEE ALSO
close(2), creat(2), dup2(2), exec(2), fcntl(2), open(2), pipe(2), privileges(5).
STANDARDS CONFORMANCE
dup(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1