第三篇了，前面两篇写的有点短，今天准备写长一点，言归正传开始工作
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devfs_automounted="no"
if [ -e "/dev/.devfsd" ]
then
mymounts="$(awk '($3 == "devfs") { print "yes"; exit 0 }' /proc/mounts)"
if [ "${mymounts}" != "yes" ]
then
rm -f /dev/.devfsd
else
devfs_automounted="yes"
fi
fi
|
这段为的是修正bug用的，具体为什么，还没有弄清楚，跳过这段，我们接下来看
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if [ "${RC_DEVICES}" = "static" ]
then
ebegin "Using existing device nodes in /dev"
eend 0
else
fellback_to_devfs="no"
case "${RC_DEVICES}" in
devfs) devfs="yes"
udev="no"
;;
udev) devfs="yes"
udev="yes"
fellback_to_devfs="yes"
;;
auto|*) devfs="yes"
udev="yes"
;;
esac
if [ "${udev}" = "yes" ]
then
if get_bootparam "noudev" || ! has_addon udev-start.sh || \
[ ${devfs_automounted} = "yes" ] || \
[ "$(get_KV)" -lt "$(KV_to_int '2.6.0')" ]
then
udev="no"
fi
fi
if [ "${devfs}" = "yes" ]
then
if get_bootparam "nodevfs" || [ "${udev}" = "yes" ] || \
! has_addon devfs-start.sh
then
devfs="no"
fi
fi
if [[ ${udev} == "yes" ]] ; then
start_addon udev
elif [[ ${devfs} == "yes" ]] ; then
start_addon devfs
if [[ ${fellback_to_devfs} == "yes" ]] ; then
ewarn "You wanted udev but support for it was not available!"
ewarn "Please review your system after it's booted!"
fi
fi
if [[ ${devfs} == "no" && ${udev} == "no" ]] ; then
echo
einfo "The Gentoo Linux system initialization scripts have detected that"
einfo "your system does not support UDEV. Since Gentoo Linux has been"
einfo "designed with dynamic /dev in mind, it is highly suggested that you"
einfo "emerge sys-fs/udev and configure your system to use it."
einfo "Please read the Gentoo Handbook for more information!"
echo
einfo " "
echo
einfo "Thanks for using Gentoo! :)"
echo
read -t 15 -p "(hit Enter to continue or wait 15 seconds ...)"
fi
fi
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首先还是一个变量RC_DEVICES，这个变量是值是在/etc/init.d/rc里面的定义为auto，明显auto！=static所以，进入else的分支，先给变量fellback_to_devfs赋值为no，然后根据RC_DEVICES的值进行case分支语句，判断后得到 devfs="yes"，udev="yes"，然后通过这两个变量的值进行处理，下面介绍一些处理过程中的几个函数：1,get_bootparam这个函数在/sbin/functions.sh里面
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get_bootparam() {
local x copt params retval=1
[[ ! -r /proc/cmdline ]] && return 1
for copt in $(< /proc/cmdline) ; do
if [[ ${copt%=*} == "gentoo" ]] ; then
params=$(gawk -v PARAMS="${copt##*=}" '
BEGIN {
split(PARAMS, nodes, ",")
for (x in nodes)
print nodes[x]
}')
# Parse gentoo option
for x in ${params} ; do
if [[ ${x} == "$1" ]] ; then
# echo "YES"
retval=0
fi
done
fi
done
return ${retval}
}
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先是判断/proc/cmdline这个文件是否只读，我看了一下ls -l /proc/cmdline得到的结果是-r--r--r-- 1 root root 0 Apr 22 20:19 /proc/cmdline，显然是只读的，然后我们看一下/proc/cmdline的内容，cat /proc/cmdline,内容显示为root=/dev/ram0 init=/linuxrc ramdisk=8192 real_root=/dev/sda3 doscsi，然后分析上面这个函数，这个函数的作用就是把/proc/cmdline中以空格分开的参数，和函数传入的第一个参数化比较，如果相同，那么就返回为0.
2,has_addon，这个函数在/sbin/functions.sh里面
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has_addon() {
[[ -e ${svclib}/addons/$1 ]]
}
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这个函数就是检查/lib/rcscripts/addons下面是否有has_addon传入第一个参数的文件.
在回到前面的代码看看处理过程:
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if [ "${udev}" = "yes" ]
then
if get_bootparam "noudev" || ! has_addon udev-start.sh || \
[ ${devfs_automounted} = "yes" ] || \
[ "$(get_KV)" -lt "$(KV_to_int '2.6.0')" ]
then
udev="no"
fi
fi
|
根据前面的分析,可以检测到 udev_start.sh这个文件是有的，所以udev=yes
|
if [ "${devfs}" = "yes" ]
then
if get_bootparam "nodevfs" || [ "${udev}" = "yes" ] || \
! has_addon devfs-start.sh
then
devfs="no"
fi
fi
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同上devfs=yes,在下面一个重要的函数就是start_addon了，我们来看看，start_addon到底干了什么呢？
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start_addon() {
local addon="$1"
(import_addon "${addon}-start.sh")
return 0
}
import_addon() {
local addon="${svclib}/addons/$1"
if has_addon $1 ; then
source "${addon}"
return 0
fi
return 1
}
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其实就是source一下/lib/rcscripts/addons/xxxx-start.sh.对应上面的代码就是source /lib/rcscripts/addons/udev-start.sh和devfs-start.sh
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if [[ ${fellback_to_devfs} == "yes" ]] ;
if [[ ${devfs} == "no" && ${udev} == "no" ]];
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这两个判断是不成立，根据上面的判断可以得到，如果这两个判断成立的话，说明出错误拉！！！！！！
昨天比较忙，没有及时更新，今天继续！！！！！！不过呢，马上就要出现一句经典的话了，各位观众，大家听好了To Be Continue!!!!!!!!!!!
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