109 lines
4.9 KiB
Groff
109 lines
4.9 KiB
Groff
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.\" Copyright 1989 The Open Group
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.\"
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.\" Permission to use, copy, modify, distribute, and sell this software and its
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.\" documentation for any purpose is hereby granted without fee, provided that
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.\" the above copyright notice appear in all copies and that both that
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.\" copyright notice and this permission notice appear in supporting
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.\" documentation.
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.\"
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.\" The above copyright notice and this permission notice shall be included
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.\" in all copies or substantial portions of the Software.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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.\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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.\" IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
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.\" OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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.\" ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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.\" OTHER DEALINGS IN THE SOFTWARE.
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.\"
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.\" Except as contained in this notice, the name of The Open Group shall
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.\" not be used in advertising or otherwise to promote the sale, use or
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.\" other dealings in this Software without prior written authorization
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.\" from The Open Group.
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.\"
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.\" Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
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.\"
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.\" Permission is hereby granted, free of charge, to any person obtaining a
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.\" copy of this software and associated documentation files (the "Software"),
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.\" to deal in the Software without restriction, including without limitation
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.\" the rights to use, copy, modify, merge, publish, distribute, sublicense,
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.\" and/or sell copies of the Software, and to permit persons to whom the
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.\" Software is furnished to do so, subject to the following conditions:
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.\"
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.\" The above copyright notice and this permission notice (including the next
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.\" paragraph) shall be included in all copies or substantial portions of the
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.\" Software.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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.\" IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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.\" FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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.\" THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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.\" LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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.\" FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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.\" DEALINGS IN THE SOFTWARE.
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.\"
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.\"
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.TH XDMSHELL __appmansuffix__ __xorgversion__
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.SH NAME
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xdmshell \- shell for starting xdm on login
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.SH SYNOPSIS
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.B BINDIR/xdmshell
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.SH DESCRIPTION
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.I Xdmshell
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can be used on systems that are configured to start a console in text mode by
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default, to allow users to start the X display manager by logging in as a
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special user with the shell set to the xdmshell program.
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.LP
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Many servers set the keyboard to do non-blocking I/O under the assumption that
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they are the only programs attempting to read from the keyboard.
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Unfortunately, some versions of \fIgetty\fP(__adminmansuffix__) will
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immediately see a continuous stream of zero-length reads which they interpret
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as end-of-file indicators. Eventually, \fIinit\fP(__adminmansuffix__) will
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disable logins on that line until somebody types the following as root:
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.RS
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\# kill -HUP 1
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.RE
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.LP
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On some platforms, one alternative is to disable logins on the console
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and always run \fIxdm\fP(__appmansuffix__) from \fI/etc/inittab\fP.
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.LP
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Another approach is to set up an account whose shell is the \fIxdmshell\fP
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program found in the xdm distribution. This program is not installed by
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default so that site administrators will examine it to see if it meets their
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needs. The \fIxdmshell\fP utility makes sure that it is being run from the
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appropriate type of terminal, starts \fIxdm\fP, waits for it to finish, and
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then resets the console if necessary. If the \fIxdm\fP resources file
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(specified by the \fIDisplayManager*resources\fP entry in the
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\fIxdm-config\fP file) contains a binding to the \fIabort-display\fP action
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similar to the following
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.RS
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xlogin*login.translations: #override Ctrl<Key>R: abort-display()
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.RE
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the console can then by restored by pressing the indicated key
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(Control-R in the above example) in the \fIxdm\fP login window.
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.LP
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.ne 10
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The \fIxdmshell\fP program is usually
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installed setuid to root but executable only by members of a special group,
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of which the only member is the account which has \fIxdmshell\fP as its shell:
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.RS
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.nf
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% grep xdm /etc/passwd
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x::101:51:Account for starting up X:/tmp:BINDIR/xdmshell
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% grep 51 /etc/group
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xdmgrp:*:51:
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% ls -lg BINDIR/xdmshell
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-rws--x--- 1 root xdmgrp 20338 Nov 1 01:32 BINDIR/xdmshell
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.fi
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.RE
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.LP
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If the \fIxdm\fP resources have not been configured to have a key bound to
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the \fIabort-display()\fP action, there will be no way for general users to
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login to the console directly. Whether or not this is desirable depends on
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the particular site.
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.SH "SEE ALSO"
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.IR X (__miscmansuffix__),
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.IR xdm (__appmansuffix__),
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.IR xinit (__appmansuffix__)
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