s6-linux-utils
Software
skarnet.org
 The s6-pivotchroot program 
s6-pivotchroot performs a pivot_root system call,
then changes root to the new root filesystem and executes a program.
 Interface 
     s6-pivotchroot newroot putold prog...
 -  s6-pivotchroot sets the root filesystem to newroot,
which must be a mounted filesystem entry point. The old root filesystem
will be available under putold (relative to the old root). 
-  s6-pivotchroot changes directory to the new root, performs
a chroot system call to the new root, and executes prog
with its arguments. prog is searched under the new root.