ubuntu 启动

(Intro)介绍
This will describe and explain the start-up process of .

这里将描述和解释Ubuntu Linux的启动过程

(rc2.d)
Like Debian, Ubuntu boots up in runlevel 2. Because of that, we'll find the details we want in /etc/rc2.d. Inside that directory, we find:

就像Debian，Ubuntu默认开机运行等级为2。因此，我们将在/etc/rc2.d发现我们想要的详细资料。在那个目录，我们发现：
>> sysklogd
>> klogd
>> ppp
>> portmap
>> acpid
>> alsa
>> apmd
>> autofs
>> cupsys
>> dbus-1
>> fam
>> inetd
>> makedev
>> postfix
>> powernowd
>> rsync
>> mdadm
>> atd
>> cron
>> acpi-support
>> fetchmail
>> gdm
>> rmnologin
>> stop-bootlogd

(start-stop-daemon)
An important utility to understand first is the Debian utility, start-stop-daemon. It's a simple program that manages starting and stopping running daemons. Each program under /etc/rc2.d utilizes this program to manage their process.

一个首先推定为Debian工具的重要工具，start-stop-daemon。这是一个管理程序的开始和暂停的简单程序。任何在/etc/rc2.d底下的程序利用此程序来管理他们的进程。

(init-functions)
All services run /lib/lsb/init-functions. This file contains helper functions for the start-stop-daemon program. It helps manage the pid files under /var/run and provides the text-output and logging when the status of a service changes.

所有服务运行 /lib/lsb/init-functions。此文件包含start-stop-daemon程序的助手函数。它帮助管理在/var/run下的pid文件并且在服务状态发生改变的时候提供文本输出和生成日志。

(sysklogd)
Sysklogd is the system log daemon. As the description implies, it allows the system to log messages. Options may be specified in the SYSKLOGD variable. The daemon then starts and reads its configuration from /etc/syslog.conf. More information can be found
Sysklogd是系统日志程序。作为必需的描述：它允许系统记录讯息。各种选项在变量SYSKLOGD里被指定。接着后台程序开始运行并且从/etc/syslog.conf读入配置文件。可获得更多信息。

(klogd)
Klogd provides kernel logging. Klogd will obtain kernel messages from /proc/kmsg, but if /proc doesn't exist, it will use the system call interface. All kernel messages are routed through syslog which then places them in the /var/log/kern.log file.
Klogd提供核心日志。Klogd将从/proc/kmsg获得核心讯息，但是如果/proc不存在，它将系统调用呼叫接口，所有核心讯息通过接着代替他们的syslog发送到/var/log/kern.log文件。

(ppp)
This file checks if /etc/ppp/ppp_on_boot exists and if it does, connect to the users ISP.
此文件检查/etc/ppp/ppp_on_boot文件是否存在，如果存在连接到用户ISP.

(portmap)
Portmap converts RPC calls into standard DARPA (tcp/ip) port numbers. This file reads /etc/default/portmap which tells portmap to only run on the local loopback interface.
Portmap 将RPC调用转换成标准DARPA(tcp/ip)端口号。此文件读入/etc/default/portmap告诉portmap仅仅在本地回送接口运行。

(acpid)
acpid is a power management daemon. It will sit and read /proc/acpi/event until it receives a whole line. Once then, it checks /etc/acpi/events for a qualifying action for that event. By default, Ubuntu loads the following acpi related modules: battery, ac, processor, button, fan, and thermal. More info can be found
acpid 作为电力管理程序。它将占用并读入/proc/acpi/event文件直到它收到一整行。一旦（发生事件）然后，它作为有资格的动作为那事件检查 /etc/acpi/events。默认的，Ubuntu导入以下和acpi有关的模块：battery, ac, processor, button, fan, 和thermal，可获得更多信息。

 
(alsa)
Alsa is the Advanced Linux Sound Architecture. It reads in some basic settings from /etc/default/alsa then loads up the stored alsa settings. More info can be found
Alsa 是高级Linux声音架构的意思。它从/etc/default/alsa读入一些基本设置然后装载被存储的alsa设置。可获得更多信息。

(apmd)
apmd is another power management daemon. This one really just cares about battery power, system standby, system suspend, and system resume. More info can be found
apmd是另外一个电力管理程序。这个守护程序真正关心电池电力、系统待机、系统挂起、和系统恢复。可获得更多信息。

(autofs)
autofs controls the automount daemon. autofs reads /etc/auto.master for various mount points of mounting drives.
autofs控制自动挂载程序。autofs在/etc/auto.master读入各种挂载设备的挂载点。

(cups)
cups is the Common Unix Printing System. It provides and extremely easy system for configuring a printer under linux. More info can be found here
cups是通用Unix打印系统。它为在linux下配置打印机提供非常简单的系统。此处可获得更多信息。

(dbus-1)
dbus is a system for providing Inter Process Communications between two applications. As explains, examples of this include a camera being plugged in or file monitoring. More info can be found
dbus是一个提供双应用程序间的处理通信的系统。作为解释，此例子包含一个插上电源的照相机或者文件监视器。可获得更多信息。

(famd)
famd is the File Alteration Monitor daemon. It provides a system that applications can use to detect when a file changes.
famd是文件更改监视器程序。它提供一个当文件被改变的时候能够监测的系统。
(inetd)
inetd provides a list of services and ports they run on under /etc/inetd.conf. It then listens for requests for those ports, and once received, runs that service.
inetd提供在/etc/inetd.conf下的服务列表以及相关端口。然后它监听请求端口，一旦收到，运行相关服务。

(makedev)
makedev simply re-creates a symlink from /sbin/MAKEDEV to /dev/MAKEDEV
makedev 简单的从/sbin/MAKEDEV到/dev/MAKEDEV重建一个符号连接

(postfix)
Postfix is a Mail Transport Agent or MTA. This provides local system mail transportation, and if configured correctly, internet-wide mail transportation. More info can be found
Postfix是邮件传送代理或者简称MTA。它提供本地系统邮件传递，如果配置正确，能提供Internet范围的邮件传递。可获得更多信息。

(powernowd)
powernowd is a client for cpufreq which, as the name implies, controls the CPU frequency. By using this, you may raise the frequency of your cpu when your computer may need the extra power and lower it during idle time. This is especially useful for laptops when heat is concerned.
powernowd 是一个cpufreq的客户端程序，cpufreq～顾名思义－能控制CPU频率。通过是用它，你可以提高你电脑的频率同时或许会需要额外电力，在停机的时候降低它。当与热有关时，这特别对便携电脑有用。

 

(rsync)
This would start the rsync daemon on your system but, by default, it is disabled.

这将在你的系统上开始rsync程序，但是默认他是不起作用的。

(mdadm)
mdadm manages software RAID under linux. More info can be found here

mdadm在linux下管理软件RAID。 此处可获得更多信息。

(atd)
atd is the at daemon and manages processes scheduled to run at later times.
atd是在后台并且管理过程计划为了在晚些时候运行。

(crond)
crond is the cron daemon and manages processes that may be on a repetitive schedule.
crond 是cron守护进程并且在重复的计划中管理过程。

(acpi-support)
This is just a helper script for the acpi daemon. Depending on what mode a laptop is in (battery or AC), it will set the systems power accordingly.
这仅仅是acpi程序的助手脚本。依靠便携机运行在什么方式（电池或者交流电），从而调整系统电力。

(fetchmail)
fetchmail manages retrieving email. This script checks for /etc/fetcmailrc and if it doesnt exist (it doesnt by default), then it does not start. More info can be found
fetchmail管理找回的email。此脚本检验/etc/fetcmailrc文件并且当此文件不存在的时候（默认不存在此文件），它将不运行。可获得更多信息。
(gdm)
gdm is the GNOME Display Manager. It starts X Windows and provides a graphical login screen. More info can be found
gdm是GNOME显示管理器。它开始X Window并且提供一个图形化的登录屏幕。可获得更多信息。

(rmnologin)
This script removes the /etc/rmnologin file. rmnologin prevents non-root users from logging in.
此脚本移除/etc/rmnologin文件。rmnologin防止非root用户登录系统。

(stop-bootlogd)
Just like the name implies, this stops the bootlogd daemon. bootlogd logs all strings sent to the console.

顾名思义，它结束bootlogd后台程序。bootlogd记录所有发送到控制台的字串。