The error-driven cp sequence, ending with the flag that carries the timestamp

Answer

cp nosuch.txt copy.txt cp secret.txt copy.txt cp alpha.txt copy.txt cp -f alpha.txt copy.txt cp -fp alpha.txt copy.txt ls -l alpha.txt copy.txt

Three different failures — missing source, unreadable source, unwritable destination — then -f to force, then -fp so the copy keeps the original modification time.

S&K 3e ch6 §6.3