shell_cmds/chroot/chroot.8

   1 .\" Copyright (c) 1988, 1991, 1993
   2 .\"     The Regents of the University of California.  All rights reserved.
   3 .\"
   4 .\" Redistribution and use in source and binary forms, with or without
   5 .\" modification, are permitted provided that the following conditions
   6 .\" are met:
   7 .\" 1. Redistributions of source code must retain the above copyright
   8 .\"    notice, this list of conditions and the following disclaimer.
   9 .\" 2. Redistributions in binary form must reproduce the above copyright
  10 .\"    notice, this list of conditions and the following disclaimer in the
  11 .\"    documentation and/or other materials provided with the distribution.
  12 .\" 3. All advertising materials mentioning features or use of this software
  13 .\"    must display the following acknowledgement:
  14 .\"     This product includes software developed by the University of
  15 .\"     California, Berkeley and its contributors.
  16 .\" 4. Neither the name of the University nor the names of its contributors
  17 .\"    may be used to endorse or promote products derived from this software
  18 .\"    without specific prior written permission.
  19 .\"
  20 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30 .\" SUCH DAMAGE.
  31 .\"
  32 .\"     from: @(#)chroot.8      8.1 (Berkeley) 6/9/93
  33 .\"     $NetBSD: chroot.8,v 1.7 1998/10/06 03:47:50 mrg Exp $
  34 .\"
  35 .Dd October 6, 1998
  36 .Dt CHROOT 8
  37 .Os BSD 4.3
  38 .Sh NAME
  39 .Nm chroot
  40 .Nd change root directory
  41 .Sh SYNOPSIS
  42 .Nm
  43 .Op Fl u user
  44 .Op Fl g group
  45 .Op Fl G group,group,...
  46 .Ar newroot
  47 .Op Ar command
  48 .Sh DESCRIPTION
  49 The
  50 .Nm
  51 command changes its root directory to the supplied directory
  52 .Ar newroot
  53 and exec's
  54 .Ar command ,
  55 if supplied, or an interactive copy of your shell.
  56 .Pp
  57 If the
  58 .Fl u ,
  59 .Fl g
  60 or
  61 .Fl G
  62 options are given, the user, group and group list of the process are
  63 set to these values after the chroot has taken place.  See
  64 .Xr setgid 2 ,
  65 .Xr setgroups 2 ,
  66 .Xr setuid 2 ,
  67 .Xr getgrnam 3
  68 and
  69 .Xr getpwnam 3 .
  70 .Pp
  71 Note,
  72 .Ar command
  73 or the shell are run as your real-user-id.
  74 .Sh ENVIRONMENT
  75 The following environment variable is referenced by
  76 .Nm :
  77 .Bl -tag -width SHELL
  78 .It Ev SHELL
  79 If set,
  80 the string specified by
  81 .Ev SHELL
  82 is interpreted as the name of
  83 the shell to exec.
  84 If the variable
  85 .Ev SHELL
  86 is not set,
  87 .Pa /bin/sh
  88 is used.
  89 .El
  90 .Sh SEE ALSO
  91 .Xr chdir 2 ,
  92 .Xr chroot 2 ,
  93 .Xr environ 7
  94 .Sh HISTORY
  95 The
  96 .Nm
  97 utility first appeared in
  98 .Bx 4.4 .
  99 .Sh SECURITY CONSIDERATIONS
 100 .Nm
 101 should never be installed setuid root, as it would then be possible
 102 to exploit the program to gain root privileges.