How to tell the maximum speed of copying a file using Finder or cp or rsync? [duplicate]

Solution 1:

Since I have a much newer system, I couldn't accurately test with a 119 MB file as it took less than a second to copy in Terminal. So I created several much larger files, up to 2 GB, using dd and /dev/random as the source and made duplicates. I then rebooted and then did timed copies of each of the sets, one in Terminal and the other in Finder. This way, there was nothing in the disk cache/memory during the subsequent copy operations in each app for each set.

The timings were near identical, so near as to be the same for this test purpose. I say near identical as in Terminal I used the time command and in Finder I used the second hand of the clock. So in your case, the file definitely was still in memory when the second copy operation was performed.