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📋 NAME

pivot_root - change the root filesystem

🚀 Quick Reference

Use Case	Command	Description
🔁 Change root filesystem to a local device	pivot_root /new-root /old-root	Moves current root to put_old and makes new_root the new root.
📦 Chroot after pivot_root for clean unmount	cd new_root; pivot_root . put_old; exec chroot . command	Ensures root is changed and old root can be unmounted.
🌐 Over NFS root filesystem	mount -o ro 10.0.0.1:/my_root /mnt; cd /mnt; pivot_root . old_root; exec chroot . sh -c 'umount /old_root; exec /sbin/init'	Boot from NFS root, unmount old root, start init.

📖 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 current working directory 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).

⚙️ OPTIONS

🔍 -V, --version

Display version information and exit.

❓ -h, --help

Display help text and exit.

💡 EXAMPLE

💻 Change root to local device

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

🌐 Change root over NFS

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)
• pivot_root(2)
• mount(8)
• switch_root(8)
• umount(8)

🐛 REPORTING BUGS

For bug reports, use the issue tracker at https://github.com/karelzak/util-linux/issues.

📦 AVAILABILITY

The pivot_root command is part of the util-linux package which can be downloaded from Linux Kernel Archive https://www.kernel.org/pub/linux/utils/util-linux/.

📋 NAME 🚀 Quick Reference 📖 SYNOPSIS 📝 DESCRIPTION ⚙️ OPTIONS 💡 EXAMPLE 🔗 SEE ALSO 🐛 REPORTING BUGS 📦 AVAILABILITY