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RedHat 9 (Linux i386) - man page for pivot_root (redhat section 8)

PIVOT_ROOT(8)			       Maintenance Commands			    PIVOT_ROOT(8)

       pivot_root - change the root file system

       pivot_root new_root put_old

       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).

       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 and run init:

       ifconfig lo up   # for portmap
       # configure Ethernet or such
       portmap	 # for lockd (implicitly started by mount)
       mount -o ro /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

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

Linux					   Feb 23, 2000 			    PIVOT_ROOT(8)

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