1.\" $NetBSD: chroot.2,v 1.12 1999/12/02 21:42:36 kleink Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)chroot.2 8.1 (Berkeley) 6/4/93 35.\" 36.Dd June 4, 1993 37.Dt CHROOT 2 38.Os 39.Sh NAME 40.Nm chroot 41.Nd change root directory 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.Fd #include <unistd.h> 46.Ft int 47.Fn chroot "const char *dirname" 48.Sh DESCRIPTION 49.Fa dirname 50is the address of the pathname of a directory, terminated by an ASCII NUL. 51.Fn chroot 52causes 53.Fa dirname 54to become the root directory, 55that is, the starting point for path searches of pathnames 56beginning with 57.Ql / . 58.Pp 59In order for a directory to become the root directory 60a process must have execute (search) access for that directory. 61.Pp 62If the current working directory is not at or under the new root 63directory, it is silently set to the new root directory. 64It should be noted that, on most other systems, 65.Fn chroot 66has no effect on the process's current directory. 67.Pp 68This call is restricted to the super-user. 69.Sh RETURN VALUES 70Upon successful completion, a value of 0 is returned. Otherwise, 71a value of -1 is returned and 72.Va errno 73is set to indicate an error. 74.Sh ERRORS 75.Fn chroot 76will fail and the root directory will be unchanged if: 77.Bl -tag -width Er 78.It Bq Er ENOTDIR 79A component of the path name is not a directory. 80.It Bq Er ENAMETOOLONG 81A component of a pathname exceeded 82.Dv {NAME_MAX} 83characters, or an entire path name exceeded 84.Dv {PATH_MAX} 85characters. 86.It Bq Er ENOENT 87The named directory does not exist. 88.It Bq Er EACCES 89Search permission is denied for any component of the path name. 90.It Bq Er ELOOP 91Too many symbolic links were encountered in translating the pathname. 92.It Bq Er EFAULT 93.Fa dirname 94points outside the process's allocated address space. 95.It Bq Er EIO 96An I/O error occurred while reading from or writing to the file system. 97.El 98.Sh SEE ALSO 99.Xr chdir 2 100.Sh HISTORY 101The 102.Fn chroot 103function call appeared in 104.Bx 4.2 . 105Working directory handling was changed in 106.Nx 1.4 107to prevent one way a process could use a second 108.Fn chroot 109call to a different directory to "escape" from the restricted subtree. 110