dup(2) System Calls dup(2)NAMEdup - duplicate an open file descriptor
SYNOPSIS
#include <unistd.h>
int dup(int fildes);
DESCRIPTION
The dup() function 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) function call is equivalent to:
fcntl(fildes, F_DUPFD, 0)
RETURN VALUES
Upon successful completion, a non-negative integer representing the
file descriptor is returned. Otherwise, −1 is returned and errno is set
to indicate the error.
ERRORS
The dup() function will fail if:
EBADF The fildes argument is not a valid open file descrip‐
tor.
EINTR A signal was caught during the execution of the dup()
function.
EMFILE The process has too many open files (see getrlimit(2)).
ENOLINK The fildes argument 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to that machine is no longer active.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 │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │Async-Signal-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOclose(2), creat(2), exec(2), fcntl(2), getrlimit(2), open(2), pipe(2),
dup2(3C), lockf(3C), attributes(5), standards(5)SunOS 5.10 28 Dec 1996 dup(2)
