On Mon, February 1, 2016 4:23 pm, Gordon Messmer wrote:
On 02/01/2016 01:48 PM, Valeri Galtsev wrote:
I just discovered that I couldn't even re-cite alphabet correctly today: it is /bin that you loose, but /etc alphabetically goes after /dev, so will not even loose your /etc,
I'm pretty sure none of that is correct. Once "rm" launches, all of the libraries and files that it needs are memory mapped and reference counted, so they're going to remain available while it removes the entire filesystem structure.
All true, except for: to actually write stuff permanently to hard drive (that is modify whatever the content of hard drive is) the system needs to access /dev/sda1 (I call from now /dev/sda1 device which "/" filesystem lives on), and once /dev/sda1 is deleted there will be no further hard drive write operations. There will be no way for system to access anything under /, which will cause "rm" command to fail fataly. I will kickstart install centos 7 in a moment and will do exactly this:
cd /
rm -rf /
(the first command is to avoid even "can not get CWD", which shouldn't matter ;-)
So, I'll see in a moment how much I'll loose on the drive, and will it or will it not be sufficient to rsync /boot from "twin" box, and restore /bin symlink. Will get back with either "crap, indeed I was wrong", or "yes, even on latest CentOS 7 system it is still so". Whatever the result is, I'll enjoy this experiment. Thanks for giving me incentive to do it!
Incidentally, let me know if there is anything I should change in my experiment for that to give us more definite answers that just "oh, look, I still have /etc, /home, /usr... intact on hard drive". What specifically should I do to learn that in a course of this command /sys was never touched? Any ideas?
Valeri
++++++++++++++++++++++++++++++++++++++++ Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ++++++++++++++++++++++++++++++++++++++++