Linux Commands Examples

A great documentation place for Linux commands


change the root filesystem

see also : chroot - mount - umount


pivot_root new_root put_old

add an example, a script, a trick and tips

: email address (won't be displayed)
: name

Step 2

Thanks for this example ! - It will be moderated and published shortly.

Feel free to post other examples
Oops ! There is a tiny cockup. A damn 404 cockup. Please contact the loosy team who maintains and develops this wonderful site by clicking in the mighty feedback button on the side of the page. Say what happened. Thanks!



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


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).


The pivot_root command is part of the util-linux package and is available from

see also

chroot , mount , pivot_root, umount

How can this site be more helpful to YOU ?

give  feedback