请问Ubuntu11.04启动过程

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1. irongeek 于 2011-09-06 12:58:35发表:

   Since Ubuntu 6.10 (Edgy Eft)
   Since the introduction of Upstart some time in 2006, or more relevantly 9.10 Karmic where most of the system services were converted, the boot process changed somewhat. The following information is tested on 11.04 Natty:
   
   Directories and Configs
   •/etc/init is where the upstart init configs live. While they are not scripts themselves, they essentially execute whatever is required to replace sysvinit scripts.
   •/etc/init.d is where all the traditional sysvinit scripts and the backward compatible scripts for upstart live. The backward compatible scripts basically run service myservice start instead of doing anything themselves. Some just show a notice to use the "service" command.
   •/etc/init/rc-sysinit.conf controls execution of traditional scripts added manually or with update-rc.d to traditional runlevels in /etc/rc*
   •/etc/default has configuration files allowing you to control the behaviour of both traditional sysvinit scripts and new upstart configs.
   
   Using Services
   Please note that generally, you can use either traditional sysvinit scripts and the methods of working with them as well as the new upstart configs and the command: "service" interchangeably. It is however recommended you use the new upstart methods which are both forward and backward compatible.
   Starting a Service
   
   # Traditional:
   /etc/init.d/myservice start
   # Upstart
   service myservice startStopping a Service
   
   # Traditional:
   /etc/init.d/myservice stop
   # Upstart
   service myservice stopGetting a list of Services
   
   # Traditional:
   ls /etc/init.d
   # Upstart:
   service --status-all
   
   •Note: Upstart method will show both traditional and upstart services.
   Adding a Service to Default runlevels
   
   # Traditional
   update-rc.d apache2 defaults
   
   •Upstart: there is no concept of runlevels, everything is event driven with dependencies. You would add an upstart config to /etc/init and potentially source a config file in /etc/default to allow users to override default behaviour.
   Removing a Service from Default runlevels
   
   # Traditional - Something along the lines of
   rm /etc/rc*/*myscript
   
   •Upstart: If no config is available in /etc/default, edit config in /etc/init
   
   Other Upstart Commands
   Controlling Services - interchangeable with the "service" command
   •initctl - can use in place of "service" with the commands bellow. Run initctl help.
   •start - start a service
   •stop - stop a service
   •reload - sends a SIGHUP signal to running process
   •restart - restarts a service without reloading its job config file
   •status - requests status of service
   
   Rebooting and Powering off the system
   •halt - shutdown the system then power off
   •poweroff - shutdown the system then power off
   •reboot - reboot the system
   •shutdown - bring the system down
   
   Misc Upstart Commands - you generally don't use these directly
   •init - Upstart process management daemon
   •runlevel - Backward compatibility with traditional runlevels
   •telinit - Backward compatibility with traditional runlevels
   •upstart-udev-bridge - Bridge between upstart and udev
   
   Writing Services
   The most current reference for job/service definition is available in the man page for init, available by running man 5 init. There are also some very useful pointers in The Upstart Cookbook.
   Here is an example of a simple upstart job config: /etc/init/myservice.conf
   
   # myservice - myservice job file
   
   description "my service description"
   author "Me <myself@i.com>"
   
   # Stanzas
   #
   # Stanzas control when and how a process is started and stopped
   # See a list of stanzas here: http://upstart.ubuntu.com/wiki/Stanzas#respawn
   
   # When to start the service
   start on runlevel [2345]
   
   # When to stop the service
   stop on runlevel [016]
   
   # Automatically restart process if crashed
   respawn
   
   # Essentially lets upstart know the process will detach itself to the background
   expect fork
   
   # Run before process
   pre-start script
   [ -d /var/run/myservice ] || mkdir -p /var/run/myservice
   echo "Put bash code here"
   end script
   
   # Start the process
   exec myprocess
   Helpful Tips
   1.initctl list shows new services straight away, service command might not!
   2.Check /var/log/syslog, it will show clues as to what went wrong.
   3.All scripts default to running with errexit (set -e), so any non-zero exit status will cause errors. In pre-start, this means the service won't start. 4.if you want to fire events from your legacy sysvinit scripts, for example postgres, you can add the following: ◦'initctl emit starting-postgresql’ in /etc/init.d/postgresql just before the service is started ◦‘initctl emit started-postgresql’ just after ◦As well as ‘initctl emit stopping-postgresql’ and ‘initctl emit stopped-postgresql ◦Then you can use ‘start on started-postgresql’ and ‘stop on stopping-postgresql’ in your job. See Upstart Getting Started for more details about upstart.
   [For more details about Ubuntu transitioning away from the sysv init system. See upstart.]
   
   Traditional Sysvinit and Before Ubuntu 6.10
   
   Init scripts
   
   Init scripts are the scripts located in /etc/init.d. These scripts are part of the bootup sequence of Ubuntu. During boot, they are not called directly, but through a structure of symbolic links which manage the services which are to be started in a particular runlevel. The scripts which are symlinked from /etc/rcS.d are executed first. Then the scripts in /etc/rcN.d/ are executed, with N being the chosen runlevel (default 2).
   The LSB specifies some scripts that are used for displaying the output of the initscripts. To change how the init script's startup is displayed look in to /lib/lsb/init-functions
   
   Deactivating init-scripts
   
   Method: Deleting the rc*.d links
   To deactivate a script (meaning that it will not be executed at bootup), remove the corresponding symlink from /etc/rc?.d. Do not use the update-rc.d command for this purpose! It is only used in package installation scripts, and not designed for this kind of runlevel management.
   Some people on the mailinglist complained on boot-delays because of the NTP-Server sync. To remove this issue the following command:
   sudo rm /etc/rcS.d/S51ntpdate
   
   •Problem: ◦To restore the links with the right S?? or K?? values you have to look up those values on another system or take a look at the deb-Package install scripts ...
   Method: Use chmod to deactivate a service
   A more straightforward way is to make the init script non-executable. You do that with the *chmod* command.
   sudo chmod -x /etc/init.d/myscriptAfter this the service will no longer be able to run.
   Reactivate the service with:
   sudo chmod +x /etc/init.d/myscript
   
   •Problem ◦Now you'll get an error message at boot time saying that init can't execute /etc/init.d/myscript.
   •Solution ◦To avoid this error msgs you have to modify the /etc/init.d/rc and the /etc/init.d/ scripts a bit. To do this simply download and apply the following diffs.
   
   cd /tmp
   wget http://www.ubuntulinux.org/wiki/rc.diff
   wget http://www.ubuntulinux.org/wiki/rcS.diff
   
   cd /etc/init.d
   sudo patch -p3 < /tmp/rc.diff
   sudo patch -p3 < /tmp/rcS.diff
   Method: Use sysvconfig to deactivate a service
   The SysvconfigHowTo explains the installation and use of the sysvconfig utility.
   
   Installing custom init-scripts
   To install your own script, copy it to /etc/init.d, and make it executable.
   sudo cp myscript /etc/init.d
   sudo chmod +x /etc/init.d/myscriptTo make the script run with the start argument at the end of the start sequence, and run with the stop argument at the beginning of the shutdown sequence:
   sudo update-rc.d myscript defaults 98 0298 and 02 are the start and stop sequence numbers respectively. Both are numbers between 00 and 99 and specify how early or late a service is started or killed. If a service is started late, it should be killed early and vice-versa. A good rule of thumb is to make the stop sequence number equal to 100 minus the start sequence number.
   For more information on the usage of update-rc.d
   man update-rc.d
   
   List of init scripts
   see InitScriptList
   
   Links
   •http://www.wlug.org.nz/update-rc.d%288%29
   •http://tinyurl.com/3lckz
   •http://tinyurl.com/5dock
   •http://www.debian.org/doc/debian-policy/ch-opersys.html#s-sysvinit
   
   Useful Comments
   
   From EduardoSilva Sun Dec 5 19:28:02 +0000 2004
   From: Eduardo Silva
   Date: Sun, 05 Dec 2004 19:28:02 +0000
   Subject: Instead of removing the rc*.d links, move them
   Message-ID: <20041205192802+0000@https://www.ubuntulinux.org>
   
   Instead of removing, I create a directory in my home dir, where I placed all the links I removed from the /etc/rc*.d
   
   From GyorgyNemeth Sun Dec 26 13:39:38 +0000 2004
   From: Gyorgy Nemeth
   Date: Sun, 26 Dec 2004 13:39:38 +0000
   Subject: Instead of removing, renaming
   Message-ID: <20041226133938+0000@https://www.ubuntulinux.org>
   
   If I want to disable initscript temporarily, I simply rename it from Sxxname to sxxname (without capital) It doesn't start, and the starting order information remains
   
   From FabioMarzocca Sun Apr 17 16:32:45 +0100 2005
   From: Fabio Marzocca
   Date: Sun, 17 Apr 2005 16:32:45 +0100
   Subject:
   Message-ID: <20050417163245+0100@https://www.ubuntulinux.org>
   
   Why don't simply use rcconf?? (apt-get install rcconf)
   
   From Chia Thu Apr 21 03:41:09 +0100 2005
   From: Chia
   Date: Thu, 21 Apr 2005 03:41:09 +0100
   Subject:
   Message-ID: <20050421034109+0100@www.ubuntulinux.org>
   
   Try sysv-rc-conf (text based) or ksysv (KDE based). sudo apt-get install sysv-rc-conf
   
   Try sysvconfig as well - it's also quite handy.
   
   From JoostRingoot Fri May 6 10:33:57 +0100 2005
   From: Joost Ringoot
   Date: Fri, 06 May 2005 10:33:57 +0100
   Subject: runlevel with networking and without graphical interface?
   Message-ID: <20050506103357+0100@www.ubuntulinux.org>
   
   I would like to have a runlevel with basic networksupport (and services like ssh and sftp) but without the graphical interface. This is not implemented in
   /etc/init.d/rcS
   
   When I run:
   apt-get install rcconf
   
   I get the message that rcconf package could not be found.
   
   apt-get install sysv-rc-conf
   
   tells me that the package is not available although another package points to it
   
   I would like to put this runlevel in the (grub) bootmenu, so that I can choose it at boot and not need to chmod files.
   
   suggestions are welcome.
   
   From Chia Sat May 7 06:46:56 +0100 2005
   From: Chia
   Date: Sat, 07 May 2005 06:46:56 +0100
   Subject:
   Message-ID: <20050507064656+0100@https://www.ubuntulinux.org>
   
   To apt-get sysv-rc-conf, you need to enable universe in /etc/apt/sources.list ,for easy way to do it use synaptic -> settings -> repositories, or read the unofficial ubuntu starter guide at http://www.ubuntuguide.org/
   . Also worth trying Boot-Up Manager: http://www.marzocca.net/linux/bum.htmlUbuntuBootupHowto (last edited 2011-08-18 09:16:47 by kralph)

2. 相思爱文 于 2011-09-06 06:11:12发表:

   查看ubuntu官方文档
   ubuntu使用简单，但不规范，很多深入学习linuxer，不推荐使用