I have a question about Mac's Empty Trash (Control-click on Trash on doc). First, I make sure the trash is empty. Then I copy or duplicate a pdf file in Finder(Control-C and then Control-V). Then I delete the copied file by pressing Command+delete key. Finally I empty my trash. During the empty progress, in the progress bar, I saw that there was saying "4 items to delete", then count down to 3, 2, 1 and gone. I only deleted one file. Where were the other 3 items come from?
Then I repeated this again and mode notes about my used space (command in Terminal: df -lk):
Used ...4,416 -- first my trash was empty ...8,112 -- after I copied a pdf file in Finder (size: 3,692k) ...8,112 -- after I deleted the copied pdf file in Finder (no difference) ...4,420 -- after I empty my trash.
Actually, I lose 4k space. Not sure how this can be explained? Is there any background cleaning jobs(removing any hidden and unused or unmounted files/packages) while the Trash is emptied?