I'm using Macbook Pro 2012 running Mac OS X 10.10.3 and earlier today, I was trying to install Linux on a USB drive through Terminal. I first converted the format with this:
hdiutil convert -format UDRW -o ubuntu.iso ubuntu-1xxxx.iso
Next, listed drives with:
Added my flash drive. And then ran this:
diskutil unmountDisk /dev/diskN
where N being the no. of drive from the DiskUtil list.
Here by mistake I chose the
disk0, my boot recovery in my opinion, and unmounted that.
After that I ran,
sudo dd if=./ubuntu.iso of=/dev/rdiskN bs=1m
where again N being the no of drive listed in DiskUtil list. Here again, absentmindedly I chose
disk1, the Macintosh HD, in my opinion. And suddenly after that I realized, what was happening and cancelled the process midway.
After that I tried remounting my recovery, but my Mac froze and after I tried to restart i got stuck at the prohibitory page. I tried booting into Recovery with Command+R, and tried mounting my Macintosh HD from there, but it gave me a error, that it couldn't be mounted. It asked me, to check a Disk Verification and Disk repair, I did that on my Macintosh HD and both were okay. But after that also the problem persists and I can't mount the Macintosh HD and still stuck at the prohibitory page.
I want to save my data, and want to backup my Macintosh HD, to an external hard drive.