dup – duplicate an open file descriptor|
int dup(int oldfd, int newfd)
Given a file descriptor, oldfd, referring to an open file, dup
returns a new file descriptor referring to the same file.
If newfd is –1 the system chooses the lowest available file descriptor.
Otherwise, dup will use newfd for the new file descriptor (closing
any old file associated with newfd).|
To avoid name conflicts with the underlying system, dup is a preprocessor
macro defined as p9dup; see intro(3).|