DUP(2) 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 returned from an open, pipe, or creat call, dup allocates another file descriptor synonymous 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 (approximately 19). 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. ASSEMBLER (dup = 41.) (file descriptor in r0) (new file descriptor in r1) sys dup (file descriptor in r0) The dup2 entry is implemented by adding 0100 to fildes.