CHROOT(8) Maintenance Commands and Procedures CHROOT(8)


chroot - change root directory for a command


chroot newroot command


The chroot utility causes command to be executed relative to newroot. The
meaning of any initial slash (/) in the path names is changed to newroot
for command and any of its child processes. Upon execution, the initial
working directory is newroot.

Notice that redirecting the output of command to a file, such as in:

chroot newroot command > xyz

will create the file xyz relative to the original root of command, not the
new one.

The new root path name is always relative to the current root. Even if a
chroot is currently in effect, the newroot argument is relative to the
current root of the running process.

This command can be run only by the super-user.


The exit status of chroot is the exit status of command.


The following operands are supported:

newroot The new root directory.

command The command to be executed relative to newroot.


Example 1 Using the chroot Utility

The chroot utility provides an easy way to extract tar files (see tar(1))
written with absolute filenames to a different location. It is necessary
to copy the shared libraries used by tar (see ldd(1)) to the newroot

example# mkdir -p /tmp/lib /tmp/usr/lib
example# cd /lib && cp \ \ \ \ /tmp/lib/
example# cp /usr/lib/ /tmp/usr/lib/
example# cp /usr/bin/tar /tmp
example# dd if=/dev/rmt/0 | chroot /tmp tar xvf -


cd(1), ldd(1), tar(1), chroot(2), ttyname(3C), attributes(7)


Exercise extreme caution when referencing device files in the new root file

References by routines such as ttyname(3C) to stdin, stdout, and stderr
will find that the device associated with the file descriptor is unknown
after chroot is run.

illumos March 18, 2021 illumos