I want to clean up my hdd.
While in live CD I go to terminal and enter:
<sudo dd if=/dev/zero | pv | dd of=/dev/sda>

The return is 'permission to access sda denied'

Why am I denied from live CD to run 'dd' using sudo?

Only first dd is running with sudo, it will not extend to other commands. Go root with then do your dd.

2 members found this post helpful.

Are you sure sda is the hard drive? Every once in a while a live cd makes a faux sda.

Whenever you run dd, check what the target is before you attempt the command. ALWAYS.

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Thank you, Emerson. <sudo -i> did the trick. I was able to start 'dd.' dd is running now as I write this note from a live CD. By morning I should have a clean HDD onto which I shall re-install LinuxMint 17.2.

Note that there are better ways of monitoring the progress of a dd; piping it through pv apparently slows the command down quite a bit (http://askubuntu.com/questions/21550...progress-of-dd).

Not sure filling hard drive with zeros is required prior to install Linux Mint...
I mean usually OS installers provide ways to prepare the destination disk

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Thank you, Cap'n Pinkeye. It was from that page that I learned about 'pv!'

Thanks for your thoughts, Keefaz. I think you are right, but I am desperate! Even fresh installs from live CD leave me with a clogged system presenting a jerky mouse, and Firefox that freezes the system requiring a hard shutdown. So I thought to erase everything...but Dban won't boot, probably due to secure boot setting in BIOS. BIOS is inaccessible without a password that is probably factory installed; so I cannot access the BIOS to remove the 'secure boot' setting. I figured second best is to wipe the hard drive with dd and start again with a fresh install. That is where I am at this morning, writing this to you from a live CD Mint 17.2. I will use this for a while to see if firefox crashes the system on live CD.

Recent versions of dd on fedora have a 'status=progress' option to show progress. Another alternative is to use a program like shred.

Thank you, Doug, for your response. LinuxMint17.2 and dd in combination are not new enough for the 'status=progress' option. However, the program 'pv' does show progress when included in the dd command. I have marked this thread closed. Thanks to all contributors from this generous community. I was able to run dd.