.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.\" Modified by Michael Haardt <michael@moria.de>
.\" Modified 1993-07-21 by Rik Faith <faith@cs.unc.edu>
.\" Modified 1994-08-21 by Michael Chastain <mec@shell.portal.com>
.\" Modified 1996-06-13 by aeb
.\" Modified 1996-11-06 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 1997-08-21 by Joseph S. Myers <jsm28@cam.ac.uk>
.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.TH CHROOT 2 2010-09-20 "Linux" "Linux Programmer's Manual"
.SH NAME
chroot \- change root directory
.SH SYNOPSIS
.B #include <unistd.h>
.sp
.BI "int chroot(const char *" path );
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.BR chroot ():
.ad l
.RS 4
.PD 0
.TP 4
Since glibc 2.2.2:
.nf
_BSD_SOURCE ||
    (_XOPEN_SOURCE\ >=\ 500 ||
        _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED) &&
    !(_POSIX_C_SOURCE\ >=\ 200112L || _XOPEN_SOURCE\ >=\ 600)
.TP 4
.fi
Before glibc 2.2.2: none
.PD
.RE
.ad b
.SH DESCRIPTION
.BR chroot ()
changes the root directory of the calling process to that specified in
.IR path .
This directory will be used for pathnames beginning with \fI/\fP.
The root directory is inherited by all children of the calling process.

Only a privileged process (Linux: one with the
.B CAP_SYS_CHROOT
capability) may call
.BR chroot ().

This call changes an ingredient in the pathname resolution process
and does nothing else.

This call does not change the current working directory,
so that after the call \(aq\fI.\fP\(aq can
be outside the tree rooted at \(aq\fI/\fP\(aq.
In particular, the superuser can escape from a "chroot jail"
by doing:
.nf

    mkdir foo; chroot foo; cd ..
.fi

This call does not close open file descriptors, and such file
descriptors may allow access to files outside the chroot tree.
.SH RETURN VALUE
On success, zero is returned.
On error, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
Depending on the file system, other errors can be returned.
The more general errors are listed below:
.TP
.B EACCES
Search permission is denied on a component of the path prefix.
(See also
.BR path_resolution (7).)
.\" Also search permission is required on the final component,
.\" maybe just to guarantee that it is a directory?
.TP
.B EFAULT
.I path
points outside your accessible address space.
.TP
.B EIO
An I/O error occurred.
.TP
.B ELOOP
Too many symbolic links were encountered in resolving
.IR path .
.TP
.B ENAMETOOLONG
.I path
is too long.
.TP
.B ENOENT
The file does not exist.
.TP
.B ENOMEM
Insufficient kernel memory was available.
.TP
.B ENOTDIR
A component of
.I path
is not a directory.
.TP
.B EPERM
The caller has insufficient privilege.
.SH CONFORMING TO
SVr4, 4.4BSD, SUSv2 (marked LEGACY).
This function is not part of POSIX.1-2001.
.\" SVr4 documents additional EINTR, ENOLINK and EMULTIHOP error conditions.
.\" X/OPEN does not document EIO, ENOMEM or EFAULT error conditions.
.SH NOTES
A child process created via
.BR fork (2)
inherits its parent's root directory.
The root directory is left unchanged by
.BR execve (2).

FreeBSD has a stronger
.BR jail ()
system call.
.\" FIXME . eventually say something about containers,
.\" virtual servers, etc.?
.SH SEE ALSO
.BR chdir (2),
.BR path_resolution (7)
.SH COLOPHON
This page is part of release 3.53 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
\%http://www.kernel.org/doc/man\-pages/.
