PIVOT_ROOT(8)                                         Maintenance Commands                                         PIVOT_ROOT(8)



NAME
       pivot_root - change the root file system

SYNOPSIS
       pivot_root new_root put_old

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

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

       cd new_root
       pivot_root . put_old
       exec chroot . command

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

       Note  that  exec  chroot changes the running executable, which is necessary 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 pivot_root has changed the shell's root or not).

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

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

       Mount the new root file system over NFS from 10.0.0.1:/my_root 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:/my_root /mnt
       killall portmap   # portmap keeps old root busy
       cd /mnt
       pivot_root . old_root
       exec chroot . sh -c 'umount /old_root; exec /sbin/init' \
         <dev/console >dev/console 2>&1

SEE ALSO
       chroot(1), mount(8), pivot_root(2), umount(8)

AVAILABILITY
       The  pivot_root   command   is   part   of   the   util-linux-ng   package   and   is   available   from   ftp://ftp.ker-
       nel.org/pub/linux/utils/util-linux-ng/.



Linux                                                     Feb 23, 2000                                             PIVOT_ROOT(8)