term% cat index.txt DUP(2) System Calls Manual DUP(2)
NAME
dup, dup2 - duplicate an open file descriptor
SYNOPSIS
dup(fildes)
int fildes;
dup2(fildes, fildes2)
int fildes, fildes2;
DESCRIPTION
Given a file descriptor dup allocates another file descriptor synony‐
mous with the original. The new file descriptor is returned.
In the second form of the call, fildes is a file descriptor referring
to an open file, and fildes2 is a non-negative integer less than the
maximum value allowed for file descriptors (currently 127). Dup2
causes fildes2 to refer to the same file as fildes. If fildes2 already
referred to an open file, it is closed first.
SEE ALSO
creat(2), open(2), close(2), pipe(2)
DIAGNOSTICS
The value -1 is returned if: the given file descriptor is invalid;
there are already too many open files.
DUP(2)