PIVOTROOT(8) System Administration PIVOTROOT(8)

NAME
       pivotroot - change the root filesystem

SYNOPSIS
       pivotroot newroot putold

DESCRIPTION
       pivotroot  moves  the  root  file system of the current process to the
       directory putold and makes newroot the new root file  system.   Since
       pivotroot(8)  simply  calls pivotroot(2), we refer to the man page of
       the latter for further details.

       Note that, depending on the implementation of pivotroot, root and  cwd
       of  the  caller  may or may not change. The following is a sequence for
       invoking pivotroot that works in either case, assuming that pivotroot
       and chroot are in the current PATH:

       cd newroot
       pivotroot . putold
       exec chroot . command

       Note that chroot must be available under the old root and under the new
       root, because pivotroot may or may not  have  implicitly  changed  the
       root directory of the shell.

       Note  that  exec chroot changes the running executable, which is neces‐
       sary if the old root directory should be  unmounted  afterwards.   Also
       note that standard input, output, and error may still point to a device
       on the old root file system,  keeping  it  busy.  They  can  easily  be
       changed  when  invoking  chroot (see below; note the absence of leading
       slashes to make it work whether pivotroot has changed the shell's root
       or not).

OPTIONS
       -V, version
              Output version information and exit.

       -h, help
              Display help and exit.

EXAMPLES
       Change the root file system to /dev/hda1 from an interactive shell:

       mount /dev/hda1 /new-root
       cd /new-root
       pivotroot . old-root
       exec chroot . sh dev/console 2>&1
       umount /old-root

       Mount  the new root file system over NFS from 10.0.0.1:/myroot and run
       init:

       ifconfig lo 127.0.0.1 up   # for portmap
       # configure Ethernet or such
       portmap   # for lockd (implicitly started by mount)
       mount -o ro 10.0.0.1:/myroot /mnt
       killall portmap   # portmap keeps old root busy
       cd /mnt
       pivotroot . oldroot
       exec chroot . sh -c 'umount /oldroot; exec /sbin/init' \
         dev/console 2>&1

SEE ALSO
       chroot(1), mount(8), pivotroot(2), switchroot(8), umount(8)

AVAILABILITY
       The pivotroot command is part of the util-linux package and is  avail‐
       able from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.



util-linux                        August 2011                    PIVOTROOT(8)