I have a 200gb HDD which I removed from a macbook due to several corrupt files in startup. One thing led to another and I decided that I needed to format the drive. I used the command sudo dd if=/dev/zero of=/dev/sdb which is supposed to wipe everything off of the hard drive. It is my understanding that the command writes 0's over every bit on the drive, which I would imagine must take a while. The process has been going for about 18 hours now. I can use other functions of operating system like the web browser and I can even use another terminal window, so I know the system is not frozen. Should I restart the process or let it continue on? Any advice will help. Thanks. By the way, I already noticed a post similar to this that was previously answered though the user was not using the same command as I was.