Linux系统Xwindow系统启动脚本分析

安装了Linux后当然希望能进入XWindow,象在Windows一样方便地工作,于是大家都可能用过startx命令,也可能是直接在XWindow登录界面进入XWindow。

这两种方式的XWindow启动过程有没有区别呢?如果你没有做过个性化设置可能体会不到,但如果你设置过中文输入法,不管是用SCIM还是fcitx,可能都有过设置输入法为随XWindow启动的经验。

朋友们开始修改各种启动脚本,经常可能会修改到的方法有:

1、修改/etc/X11/xinit/xinitrc

2、修改/etc/X11/Xsession

3、在/etc/X11/Xsession.d目录下增加一个自定义的脚本

4、修改$HOME/.xsession

5、修改$HOME/.xinitrc

6、修改/etc/X11/xdm/Xsession

……

总之,看起来是八仙过海各有各的神通了。这些方法有没有不同?为什么有时候明明设置好了,startx起来可以用了,但重启在XWindow管理界面登录后却不能用了?为什么有时从XWindow管理界面登录后可用,但startx后却用不了?

下面我们一起来分析一下吧。

#!/bin/sh

#

# /etc/X11/Xsession

#

# global Xsession file — used by display managers and xinit (startx)

# $Id: Xsession 2186 2005-02-11 07:11:05Z branden $

set -e

PROGNAME=Xsession

message () {

# pretty-print messages of arbitrary length; use xmessage if it

# is available and $DISPLAY is set

MESSAGE=”$PROGNAME: $*”

echo “$MESSAGE” | fold -s -w ${COLUMNS:-80} >&2

if [ -n “$DISPLAY” ] && which xmessage > /dev/null 2>&1; then

echo “$MESSAGE” | fold -s -w ${COLUMNS:-80} | xmessage -center -file –

fi

}

message_nonl () {

# pretty-print messages of arbitrary length (no trailing newline); use

# xmessage if it is available and $DISPLAY is set

MESSAGE=”$PROGNAME: $*”

echo -n “$MESSAGE” | fold -s -w ${COLUMNS:-80} >&2;

if [ -n “$DISPLAY” ] && which xmessage > /dev/null 2>&1; then

echo -n “$MESSAGE” | fold -s -w ${COLUMNS:-80} | xmessage -center -file –

fi

}

errormsg () {

# exit script with error

message “$*”

exit 1

}

internal_errormsg () {

# exit script with error; essentially a “THIS SHOULD NEVER HAPPEN” message

# One big call to message() for the sake of xmessage; if we had two then

# the user would have dismissed the error we want reported before seeing the

# request to report it.

errormsg “$*”

“Please report the installed version of the “xfree86-common””

“package and the complete text of this error message to”

“.”

}

# initialize variables for use by all session scripts

OPTIONFILE=/etc/X11/Xsession.options

SYSRESOURCES=/etc/X11/Xresources

USRRESOURCES=$HOME/.Xresources

SYSSESSIONDIR=/etc/X11/Xsession.d

USERXSESSION=$HOME/.xsession

ALTUSERXSESSION=$HOME/.Xsession

ERRFILE=$HOME/.xsession-errors

# attempt to create an error file; abort if we cannot

if touch “$ERRFILE” 2> /dev/null && [ -w “$ERRFILE” ] &&

[ ! -L “$ERRFILE” ]; then

chmod 600 “$ERRFILE”

elif ERRFILE=$(tempfile 2> /dev/null); then

if ! ln -sf “$ERRFILE” “${TMPDIR:=/tmp}/xsession-$USER”; then

message “warning: unable to symlink “$TMPDIR/xsession-$USER” to”

“”$ERRFILE”; look for session log/errors in”

“”$TMPDIR/xsession-$USER”.”

fi

else

errormsg “unable to create X session log/error file; aborting.”

fi

exec >>”$ERRFILE” 2>&1

echo “$PROGNAME: X session started for $LOGNAME at $(date)”

# sanity check; is our session script directory present?

if [ ! -d “$SYSSESSIONDIR” ]; then

errormsg “no “$SYSSESSIONDIR” directory found; aborting.”

fi

# Attempt to create a file of non-zero length in /tmp; a full filesystem can

# cause mysterious X session failures. We do not use touch, :, or test -w

# because they won’t actually create a file with contents. We also let standard

# error from tempfile and echo go to the error file to aid the user in

# determining what went wrong.

WRITE_TEST=$(tempfile)

if ! echo “*” >>”$WRITE_TEST”; then

message “warning: unable to write to ${WRITE_TEST%/*}; X session may exit”

“with an error”

fi

rm -f “$WRITE_TEST”

# Use run-parts to source every file in the session directory; we source

# instead of executing so that the variables and functions defined above

# are available to the scripts, and so that they can pass variables to each

# other.

SESSIONFILES=$(run-parts –list $SYSSESSIONDIR)

if [ -n “$SESSIONFILES” ]; then

for SESSIONFILE in $SESSIONFILES; do

. $SESSIONFILE

done

fi

exit 0

此文件的第五行“# global Xsession file — used by display managers and xinit (startx)”已经说明/etc/X11/Xsession脚本是大家公用的,无论你是用XWindow管理器(比如kdm、gdm、xdm)进入还 是通过命令行输入startx(即xinit方式)进入XWindow,都会调用此脚本程序。再看看这个脚本程序做了些什么吧。这一行 “SYSSESSIONDIR=/etc/X11/Xsession.d”定义了一个变量指向了目录/etc/X11/Xsession.d,后面又出现 一段代码:

SESSIONFILES=$(run-parts –list $SYSSESSIONDIR)

if [ -n “$SESSIONFILES” ]; then

for SESSIONFILE in $SESSIONFILES; do

. $SESSIONFILE

done

fi

显然这里是搜索了目录/etc/X11/Xsession.d里面所有的脚本并一一执行完毕。

同时请注意有这么两行:

USERXSESSION=$HOME/.xsession

ALTUSERXSESSION=$HOME/.Xsession

在这里并没有看到使用这两个变量,那么在这个脚本里定义来做什么?下面再看一下脚本/etc/X11/Xsession.d/50xfree86-common_determine-startup里的内容,原文如下:

# $Id: 50xfree86-common_determine-startup 1437 2004-05-23 03:18:32Z branden $

# This file is sourced by Xsession(5), not executed.

# If no X session startup program was passed to the Xsession script as an

# argument (e.g., by the display manager), or if that program was not

# executable, fall back to looking for a user’s custom X session script, if

# allowed by the options file.

if [ -z “$STARTUP” ]; then

if grep -qs ^allow-user-xsession “$OPTIONFILE”; then

for STARTUPFILE in “$USERXSESSION” “$ALTUSERXSESSION”; do

if [ -e “$STARTUPFILE” ]; then

if [ -x “$STARTUPFILE” ]; then

STARTUP=”$STARTUPFILE”

else

STARTUP=”sh $STARTUPFILE”

fi

break

fi

done

fi

fi

# If there is still nothing to use for a startup program, try the system

# default session manager, window manager, and terminal emulator.

if [ -z “$STARTUP” ]; then

if [ -x /usr/bin/x-session-manager ]; then

STARTUP=x-session-manager

elif [ -x /usr/bin/x-window-manager ]; then

STARTUP=x-window-manager

elif [ -x /usr/bin/x-terminal-emulator ]; then

STARTUP=x-terminal-emulator

fi

fi

# If we still have not found a startup program, give up.

if [ -z “$STARTUP” ]; then

ERRMSG=”unable to start X session —”

if grep -qs ^allow-user-xsession “$OPTIONFILE”; then

ERRMSG=”$ERRMSG no “$USERXSESSION” file, no “$ALTUSERXSESSION” file,”

fi

errormsg “$ERRMSG no session managers, no window managers, and no terminal”

“emulators found; aborting.”

fi

# vim:set ai et sts=2 sw=2 tw=80:

这一行“# This file is sourced by Xsession(5), not executed.”证明脚本是被之前的

/etc/X11/Xsession调用的,而后面这一段:

for STARTUPFILE in “$USERXSESSION” “$ALTUSERXSESSION”; do

if [ -e “$STARTUPFILE” ]; then

if [ -x “$STARTUPFILE” ]; then

STARTUP=”$STARTUPFILE”

else

STARTUP=”sh $STARTUPFILE”

fi

break

fi

done

更证明了这一点。在这里脚本搜索用户目录$HOME下的.xsession或.Xsession脚本来执行。

(在/etc/X11/Xsession.d目录下还有一些脚本,这里就不再分析了,各位有兴趣可以自己看看)

另外来看看/etc/X11/xinit/xinitrc这个脚本,其原文内容如下:

##!/bin/sh

## $Xorg: xinitrc.cpp,v 1.3 2000/08/17 19:54:30 cpqbld Exp $

#

## /etc/X11/xinit/xinitrc

##

## global xinitrc file, used by all X sessions started by xinit (startx)

#

## invoke global X session script

. /etc/X11/Xsession

注意这一句“## global xinitrc file, used by all X sessions started by xinit (startx)”,这说明这个脚本只被xinit调用(即用户输入startx时)。而其执行的最后还是执行了/etc/X11/Xsession脚 本。而用户如果用其它XWindow管理界面登录系统时这个脚本里的内容是不会被执行的。最后再来看看/etc/X11/xdm/Xsession这个脚 本吧,其原文内容如下:

#!/bin/sh

#

# $Xorg: Xsession,v 1.4 2000/08/17 19:54:17 cpqbld Exp $

#

#

#

#

# $XFree86: xc/programs/xdm/config/Xsession,v 1.3 2001/01/17 23:45:24 dawes Exp $

# invoke global X session script

. /etc/X11/Xsession

从内容来看,也是最终执行了/etc/X11/Xsession。

再看看/etc/X11里面的目录结构:

X Xsession.d cursors gdm rstart xinit

XF86Config-4 Xsession.options default-display-manager lbxproxy sysconfig xkb

Xresources Xwrapper.config fonts proxymngr twm xserver

Xsession app-defaults fs rgb.txt xdm xsm

显然,这里把xinit和xdm、twm及gdm是分开的,在xinit里执行的脚本是不会被xdm里的脚本调用的。从上面对代码的分析,大家 可以看到:其实XWindow执行的关键脚本是/etc/X11/Xsession,这个脚本会去 /etc/X11/Xsession.d目录里搜索脚本执行,也会去$HOME/下搜索脚本运行,而其它目录xinit、xdm等里面的脚本都会去调用 /etc/X11/Xsession这个脚本。

所以,如果你想把中文输入法fcitx、SCIM等设置成随Xwindow启动,比如要加入如下脚本:

export LC_CTYPE=zh_CN.GBK

export XMODIFIERS=”@im=fcitx”

export XIM=fcitx

export XIM_PROGRAM=fcitx

fcitx

那么可以用如下几种方法:

1、加到/etc/X11/Xsession。这种方法对所有启动方法都管理。

2、在/etc/X11/Xsession.d目录里自己写一个脚本,这种方法也对所有启动方法都管理。

3、在$HOME目录下生成.xsession或.Xsession脚本,这种方法也对当前登录用户有效。

4、加到/etc/X11/xinit/xinitrc脚本里。这个方法只对xinit方式(即命令行输入startx)管用。

5、加到/etc/X11/xdm/xsession脚本里,只对用xdm管理界面登录的方式管用。

from  http://www.soft6.com/html/tech/17/173854.shtml




coded by nessus
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