cp SRC /proc/self/fd/1| pv -s SIZE -p-e-r|cp/proc/self/fd/0 DST
#cp does not accept to write to standard output by default. It will fail if no input or output is given. So, in order to make it pipe to pv, we use /proc/self/fd/N. fd 0 represent standard input, fd 1 standard output and fd 2 standard error (we don't need that one for this purpose).