Today my problem was with dd and my MBP 2010.
Not having a linux machine ready I usually use my Mac for Unix commands. I was trying to dd a Raspberry’s image into a fresh SD card, but for some reason the console kept telling me “permission denied”.
By googling a bit I found out that this one is a common problem in MBP 2010: inside the built in SD reader slot there’s a mechanical switch that “reads” the SD’s lock pin and sometimes it gets stuck in lock position.
The solution? Blowing like I was doing a spirometry inside the slot unlocked the pin, like the old day where we all blew into Nintendo’s cartdriges.