NAME

chroot —

change root directory

SYNOPSIS

chroot [-G group[,group ...]] [-g group] [-u user] [-n] newroot [command [arg ...]]

DESCRIPTION

The chroot utility changes its current and root directories to the supplied directory newroot and then exec's command with provided arguments, if supplied, or an interactive copy of the user's login shell.

The options are as follows:

-G group[,group ...]: Run the command with the permissions of the specified groups.
-g group: Run the command with the permissions of the specified group.
-u user: Run the command as the user.
-n: Use the PROC_NO_NEW_PRIVS_CTL procctl(2) command before chrooting, effectively disabling SUID/SGID bits for the calling process and its descendants. If security.bsd.unprivileged_chroot sysctl is set to 1, it will make it possible to chroot without superuser privileges.

ENVIRONMENT

The following environment variable is referenced by chroot:

SHELL: If set, the string specified by SHELL is interpreted as the name of the shell to exec. If the variable SHELL is not set, /bin/sh is used.

EXAMPLES

Example 1: Chrooting into a New Root Directory

The following command opens the csh(1) shell after chrooting to the standard root directory.

#
 chroot / /bin/csh

Example 2: Execution of a Command with a Changed Root Directory

The following command changes a root directory with chroot and then runs ls(1) to list the contents of /sbin.

#
 chroot /tmp/testroot ls /sbin

HISTORY

The chroot utility first appeared in AT&T System III UNIX and 4.3BSD-Reno.