dup - duplicate an open file descriptor
int dup(int fildes);
The dup() function returns a new file descriptor having the
following in common with the original open file descriptor
o same open file (or pipe)
o same file pointer (that is, both file descriptors
share one file pointer)
o 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)
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.
The dup() function will fail if:
EBADF The fildes argument is not a valid open file descrip-
EINTR A signal was caught during the execution of the dup()
The process has too many open files (see
The fildes argument is on a remote machine and the
link to that machine is no longer active.
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | Async-Signal-Safe |
close(2), creat(2), exec(2), fcntl(2), getrlimit(2),
open(2), pipe(2), dup2(3C), lockf(3C), attributes(5)
Man(1) output converted with