CentOS-6.9
I am trying to verify a locally created dvd. I am using sha256sum in this fashion: sha256sum /dev/sr0
Which gave this result:
sha256sum: /dev/sr0: Input/output error
So I tried this: sha256sum /dev/cdrom
Which, after some time, also produces:
sha256sum: /dev/cdrom: Input/output error
What does this mean and how do I fix it?