I accidentally changed permission to 000 on symlink:
/lib64/ld-linux-x86-64.so.2
In effect ubuntu 15.10 can't execute any bash command (binary). In this situation chroot from live cd is not working. System is not launching (kernel panic). Rescue mode also is not launching. How to (restore permissions of this symlink and) make system bootable?
I figured it out. I mislead myself because symlink:
shows lrwxrwxrwx permissions. It directs to this shared object :
Which (permissions were changed to 000) is dynamic linker/loader. It finds and load the shared libraries needed by a program, prepare the program to run, and then run it. It lost permissions to do anything, so it couldn't launch any needed library making system unbootale.
Executing (from live system):
solve the problem.
You have to boot from CD oder USB. Or mount the harddrive into another PC.