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 specified groups as supplementary groups.
- -g group
-
Run the command with the specified group as the real, effective and saved groups.
- -u user
-
Run the command with the specified user as the real, effective and saved users.
- -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
SEE ALSO
chdir(2), chroot(2), setgid(2), setgroups(2), setuid(2), getgrnam(3), environ(7), jail(8)
HISTORY
The chroot utility first appeared in AT&T System III UNIX and 4.3BSD-Reno.