switch_root - switch to another filesystem as the root of the mount tree
switch_root newroot init [arg...]
switch_root moves already mounted /proc, /dev, /sys and /run to newroot and makes newroot the new root filesystem and starts init process.
WARNING: switch_root removes recursively all files and directories on the current root filesystem.
|-h, --help||Display help text and exit.|
|-V, --version||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
The switch_root command is part of the util-linux package and is available from https://www.kernel.org/pub/linux/utils/util-linux/.