switch_root - switch to another filesystem as the root of the mount tree
switch_root moves already mounted
newroot the new root filesystem and starts
WARNING: switch_root removes recursively all files and directories on the current root filesystem.
Display help text and exit.
Display version information and exit.
switch_root returns 0 on success and 1 on failure.
switch_root will fail to function if
newroot is not the root of a mount. If you want to switch root
into a directory that does not meet this requirement then you can first
use a bind-mounting trick to turn any directory into a mount point:
mount --bind $DIR $DIR