From d592e68b58f12b4f81d258e424941677c22030a5 Mon Sep 17 00:00:00 2001 From: ChrisLeeGit Date: Sun, 31 Jul 2016 19:24:56 +0800 Subject: [PATCH] =?UTF-8?q?=E5=AE=8C=E6=88=90=E7=BF=BB=E8=AF=91=EF=BC=9AHo?= =?UTF-8?q?w=20to=20Configure=20and=20Troubleshoot=20Grand=20Unified=20Boo?= =?UTF-8?q?tloader=20(GRUB)?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...leshoot Grand Unified Bootloader (GRUB).md | 187 ------------------ ...leshoot Grand Unified Bootloader (GRUB).md | 184 +++++++++++++++++ 2 files changed, 184 insertions(+), 187 deletions(-) delete mode 100644 sources/tech/LFCS/Part 13 - How to Configure and Troubleshoot Grand Unified Bootloader (GRUB).md create mode 100644 translated/tech/LFCS/Part 13 - How to Configure and Troubleshoot Grand Unified Bootloader (GRUB).md diff --git a/sources/tech/LFCS/Part 13 - How to Configure and Troubleshoot Grand Unified Bootloader (GRUB).md b/sources/tech/LFCS/Part 13 - How to Configure and Troubleshoot Grand Unified Bootloader (GRUB).md deleted file mode 100644 index 2d1cbef467..0000000000 --- a/sources/tech/LFCS/Part 13 - How to Configure and Troubleshoot Grand Unified Bootloader (GRUB).md +++ /dev/null @@ -1,187 +0,0 @@ -Being translated by ChrisLeeGit - -Part 13 - LFCS: How to Configure and Troubleshoot Grand Unified Bootloader (GRUB) -===================================================================================== - -Because of the changes in the LFCS exam requirements effective Feb. 2, 2016, we are adding the necessary topics to the [LFCS series][1] published here. To prepare for this exam, your are highly encouraged to use the [LFCE series][2] as well. - -![](http://www.tecmint.com/wp-content/uploads/2016/03/Configure-Troubleshoot-Grub-Boot-Loader.png) ->LFCS: Configure and Troubleshoot Grub Boot Loader – Part 13 - -In this article we will introduce you to GRUB and explain why a boot loader is necessary, and how it adds versatility to the system. - -The [Linux boot process][3] from the time you press the power button of your computer until you get a fully-functional system follows this high-level sequence: - -* 1. A process known as **POST** (**Power-On Self Test**) performs an overall check on the hardware components of your computer. -* 2. When **POST** completes, it passes the control over to the boot loader, which in turn loads the Linux kernel in memory (along with **initramfs**) and executes it. The most used boot loader in Linux is the **GRand Unified Boot loader**, or **GRUB** for short. -* 3. The kernel checks and accesses the hardware, and then runs the initial process (mostly known by its generic name “**init**”) which in turn completes the system boot by starting services. - -In Part 7 of this series (“[SysVinit, Upstart, and Systemd][4]”) we introduced the [service management systems and tools][5] used by modern Linux distributions. You may want to review that article before proceeding further. - -### Introducing GRUB Boot Loader - -Two major **GRUB** versions (**v1** sometimes called **GRUB Legacy** and **v2**) can be found in modern systems, although most distributions use **v2** by default in their latest versions. Only **Red Hat Enterprise Linux 6** and its derivatives still use **v1** today. - -Thus, we will focus primarily on the features of **v2** in this guide. - -Regardless of the **GRUB** version, a boot loader allows the user to: - -* 1). modify the way the system behaves by specifying different kernels to use, -* 2). choose between alternate operating systems to boot, and -* 3). add or edit configuration stanzas to change boot options, among other things. - -Today, **GRUB** is maintained by the **GNU** project and is well documented in their website. You are encouraged to use the [GNU official documentation][6] while going through this guide. - -When the system boots you are presented with the following **GRUB** screen in the main console. Initially, you are prompted to choose between alternate kernels (by default, the system will boot using the latest kernel) and are allowed to enter a **GRUB** command line (with `c`) or edit the boot options (by pressing the `e` key). - -![](http://www.tecmint.com/wp-content/uploads/2016/03/GRUB-Boot-Screen.png) ->GRUB Boot Screen - -One of the reasons why you would consider booting with an older kernel is a hardware device that used to work properly and has started “acting up” after an upgrade (refer to [this link][7] in the AskUbuntu forums for an example). - -The **GRUB v2** configuration is read on boot from `/boot/grub/grub.cfg` or `/boot/grub2/grub.cfg`, whereas `/boot/grub/grub.conf` or `/boot/grub/menu.lst` are used in **v1**. These files are NOT to be edited by hand, but are modified based on the contents of `/etc/default/grub` and the files found inside `/etc/grub.d`. - -In a **CentOS 7**, here’s the configuration file that is created when the system is first installed: - -``` -GRUB_TIMEOUT=5 -GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)" -GRUB_DEFAULT=saved -GRUB_DISABLE_SUBMENU=true -GRUB_TERMINAL_OUTPUT="console" -GRUB_CMDLINE_LINUX="vconsole.keymap=la-latin1 rd.lvm.lv=centos_centos7-2/swap crashkernel=auto vconsole.font=latarcyrheb-sun16 rd.lvm.lv=centos_centos7-2/root rhgb quiet" -GRUB_DISABLE_RECOVERY="true" -``` - -In addition to the online documentation, you can also find the GNU GRUB manual using info as follows: - -``` -# info grub -``` - -If you’re interested specifically in the options available for /etc/default/grub, you can invoke the configuration section directly: - -``` -# info -f grub -n 'Simple configuration' -``` - -Using the command above you will find out that `GRUB_TIMEOUT` sets the time between the moment when the initial screen appears and the system automatic booting begins unless interrupted by the user. When this variable is set to `-1`, boot will not be started until the user makes a selection. - -When multiple operating systems or kernels are installed in the same machine, `GRUB_DEFAULT` requires an integer value that indicates which OS or kernel entry in the GRUB initial screen should be selected to boot by default. The list of entries can be viewed not only in the splash screen shown above, but also using the following command: - -### In CentOS and openSUSE: - -``` -# awk -F\' '$1=="menuentry " {print $2}' /boot/grub2/grub.cfg -``` - -### In Ubuntu: - -``` -# awk -F\' '$1=="menuentry " {print $2}' /boot/grub/grub.cfg -``` - -In the example shown in the below image, if we wish to boot with the kernel version **3.10.0-123.el7.x86_64** (4th entry), we need to set `GRUB_DEFAULT` to `3` (entries are internally numbered beginning with zero) as follows: - -``` -GRUB_DEFAULT=3 -``` - -![](http://www.tecmint.com/wp-content/uploads/2016/03/Boot-System-with-Old-Kernel-Version.png) ->Boot System with Old Kernel Version - -One final GRUB configuration variable that is of special interest is `GRUB_CMDLINE_LINUX`, which is used to pass options to the kernel. The options that can be passed through GRUB to the kernel are well documented in the [Kernel Parameters file][8] and in [man 7 bootparam][9]. - -Current options in my **CentOS 7** server are: - -``` -GRUB_CMDLINE_LINUX="vconsole.keymap=la-latin1 rd.lvm.lv=centos_centos7-2/swap crashkernel=auto vconsole.font=latarcyrheb-sun16 rd.lvm.lv=centos_centos7-2/root rhgb quiet" -``` - -Why would you want to modify the default kernel parameters or pass extra options? In simple terms, there may be times when you need to tell the kernel certain hardware parameters that it may not be able to determine on its own, or to override the values that it would detect. - -This happened to me not too long ago when I tried **Vector Linux**, a derivative of **Slackware**, on my 10-year old laptop. After installation it did not detect the right settings for my video card so I had to modify the kernel options passed through GRUB in order to make it work. - -Another example is when you need to bring the system to single-user mode to perform maintenance tasks. You can do this by appending the word single to `GRUB_CMDLINE_LINUX` and rebooting: - -``` -GRUB_CMDLINE_LINUX="vconsole.keymap=la-latin1 rd.lvm.lv=centos_centos7-2/swap crashkernel=auto vconsole.font=latarcyrheb-sun16 rd.lvm.lv=centos_centos7-2/root rhgb quiet single" -``` - -After editing `/etc/defalt/grub`, you will need to run `update-grub` (Ubuntu) or `grub2-mkconfig -o /boot/grub2/grub.cfg` (**CentOS** and **openSUSE**) afterwards to update `grub.cfg` (otherwise, changes will be lost upon boot). - -This command will process the boot configuration files mentioned earlier to update `grub.cfg`. This method ensures changes are permanent, while options passed through GRUB at boot time will only last during the current session. - -### Fixing Linux GRUB Issues - -If you install a second operating system or if your GRUB configuration file gets corrupted due to human error, there are ways you can get your system back on its feet and be able to boot again. - -In the initial screen, press `c` to get a GRUB command line (remember that you can also press `e` to edit the default boot options), and use help to bring the available commands in the GRUB prompt: - -![](http://www.tecmint.com/wp-content/uploads/2016/03/Fix-Grub-Issues-in-Linux.png) ->Fix Grub Configuration Issues in Linux - -We will focus on **ls**, which will list the installed devices and filesystems, and we will examine what it finds. In the image below we can see that there are 4 hard drives (`hd0` through `hd3`). - -Only `hd0` seems to have been partitioned (as evidenced by msdos1 and msdos2, where 1 and 2 are the partition numbers and msdos is the partitioning scheme). - -Let’s now examine the first partition on `hd0` (**msdos1**) to see if we can find GRUB there. This approach will allow us to boot Linux and there use other high level tools to repair the configuration file or reinstall GRUB altogether if it is needed: - -``` -# ls (hd0,msdos1)/ -``` - -As we can see in the highlighted area, we found the `grub2` directory in this partition: - -![](http://www.tecmint.com/wp-content/uploads/2016/03/Find-Grub-Configuration.png) ->Find Grub Configuration - -Once we are sure that GRUB resides in (**hd0,msdos1**), let’s tell GRUB where to find its configuration file and then instruct it to attempt to launch its menu: - -``` -set prefix=(hd0,msdos1)/grub2 -set root=(hd0,msdos1) -insmod normal -normal -``` - -![](http://www.tecmint.com/wp-content/uploads/2016/03/Find-and-Launch-Grub-Menu.png) ->Find and Launch Grub Menu - -Then in the GRUB menu, choose an entry and press **Enter** to boot using it. Once the system has booted you can issue the `grub2-install /dev/sdX` command (change `sdX` with the device you want to install GRUB on). The boot information will then be updated and all related files be restored. - -``` -# grub2-install /dev/sdX -``` - -Other more complex scenarios are documented, along with their suggested fixes, in the [Ubuntu GRUB2 Troubleshooting guide][10]. The concepts explained there are valid for other distributions as well. - -### Summary - -In this article we have introduced you to GRUB, indicated where you can find documentation both online and offline, and explained how to approach an scenario where a system has stopped booting properly due to a bootloader-related issue. - -Fortunately, GRUB is one of the tools that is best documented and you can easily find help either in the installed docs or online using the resources we have shared in this article. - -Do you have questions or comments? Don’t hesitate to let us know using the comment form below. We look forward to hearing from you! - --------------------------------------------------------------------------------- - -via: http://www.tecmint.com/linux-basic-shell-scripting-and-linux-filesystem-troubleshooting/ - -作者：[Gabriel Cánepa][a] -译者：[ChrisLeeGit](https://github.com/chrisleegit) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: http://www.tecmint.com/author/gacanepa/ -[1]: http://www.tecmint.com/sed-command-to-create-edit-and-manipulate-files-in-linux/ -[2]: http://www.tecmint.com/installing-network-services-and-configuring-services-at-system-boot/ -[3]: http://www.tecmint.com/linux-boot-process/ -[4]: http://www.tecmint.com/linux-boot-process-and-manage-services/ -[5]: http://www.tecmint.com/best-linux-log-monitoring-and-management-tools/ -[6]: http://www.gnu.org/software/grub/manual/ -[7]: http://askubuntu.com/questions/82140/how-can-i-boot-with-an-older-kernel-version -[8]: https://www.kernel.org/doc/Documentation/kernel-parameters.txt -[9]: http://man7.org/linux/man-pages/man7/bootparam.7.html -[10]: https://help.ubuntu.com/community/Grub2/Troubleshooting diff --git a/translated/tech/LFCS/Part 13 - How to Configure and Troubleshoot Grand Unified Bootloader (GRUB).md b/translated/tech/LFCS/Part 13 - How to Configure and Troubleshoot Grand Unified Bootloader (GRUB).md new file mode 100644 index 0000000000..d8b7b294e2 --- /dev/null +++ b/translated/tech/LFCS/Part 13 - How to Configure and Troubleshoot Grand Unified Bootloader (GRUB).md @@ -0,0 +1,184 @@ +LFCS 系列第十三讲：如何配置并排除 GNU 引导加载程序（GRUB）故障 +===================================================================================== + +由于 LFCS 考试需求的变动已于 2016 年 2 月 2 日生效，因此我们向 [LFCS 系列][1] 添加了一些必要的话题。为了准备认证考试，我们也强烈推荐你去看 [LFCE 系列][2]。 + +![](http://www.tecmint.com/wp-content/uploads/2016/03/Configure-Troubleshoot-Grub-Boot-Loader.png) +>LFCS 系列第十三讲：配置并排除 Grub 引导加载程序故障。 + +本文将会向你介绍 GRUB 的知识，并会说明你为什么需要一个引导加载程序，以及它是如何增强系统通用性的。 + +[Linux 引导过程][3] 是从你按下你的电脑电源键开始，直到你拥有一个全功能的系统为止，整个过程遵循着这样的高层次顺序： + +* 1. 一个叫做 **POST**（**上电自检**）的过程会对你的电脑硬件组件做全面的检查。 +* 2. 当 **POST** 完成后，它会把控制权转交给引导加载程序，接下来引导加载程序会将 Linux 内核（以及 **initramfs**）加载到内存中并执行。 +* 3. 内核首先检查并访问硬件，然后运行初始进程（主要以它的通用名 **init** 而为人熟知），接下来初始进程会启动一些服务，最后完成系统启动过程。 + +在该系列的第七讲（“[SysVinit, Upstart, 和 Systemd][4]”）中，我们介绍了现代 Linux 发行版使用的一些服务管理系统和工具。在继续学习之前，你可能想要回顾一下那一讲的知识。 + +### GRUB 引导装载程序介绍 + +在现代系统中，你会发现有两种主要的 **GRUB** 版本（一种是偶尔被成为 **GRUB Legacy** 的 **v1** 版本，另一种则是 **v2** 版本），虽说多数最新版本的发行版系统都默认使用了 **v2** 版本。如今，只有 **红帽企业版 Linux 6** 及其衍生系统仍在使用 **v1** 版本。 + +因此，在本指南中，我们将着重关注 **v2** 版本的功能。 + +不管 **GRUB** 的版本是什么，一个引导加载程序都允许用户： + +* 1). 通过指定使用不同的内核来修改系统的表现方式； +* 2). 从多个操作系统中选择一个启动； +* 3). 添加或编辑配置节点来改变启动选项等。 + +如今，**GNU** 项目负责维护 **GRUB**，并在它们的网站上提供了丰富的文档。当你在阅读这篇指南时，我们强烈建议你看下 [GNU 官方文档][6]。 + +当系统引导时，你会在主控制台看到如下的 **GRUB** 画面。最开始，你可以根据提示在多个内核版本中选择一个内核（默认情况下，系统将会使用最新的内核启动），并且可以进入 **GRUB** 命令行模式（使用 `c` 键），或者编辑启动项（按下 `e` 键）。 + +![](http://www.tecmint.com/wp-content/uploads/2016/03/GRUB-Boot-Screen.png) +> GRUB 启动画面 + +你会考虑使用一个旧版内核启动的原因之一是之前工作正常的某个硬件设备在一次升级后出现了“怪毛病（acting up）”（例如，你可以参考 AskUbuntu 论坛中的 [这条链接][7]）。 + +**GRUB v2** 的配置文件会在启动时从 `/boot/grub/grub.cfg` 或 `/boot/grub2/grub.cfg` 文件中读取，而 **GRUB v1** 使用的配置文件则来自 `/boot/grub/grub.conf` 或 `/boot/grub/menu.lst`。这些文件不能直接手动编辑，而是根据 `/etc/default/grub` 的内容和 `/etc/grub.d` 目录中的文件来修改的。 + +在 **CentOS 7** 上，当系统最初完成安装后，会生成如下的配置文件： + +``` +GRUB_TIMEOUT=5 +GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)" +GRUB_DEFAULT=saved +GRUB_DISABLE_SUBMENU=true +GRUB_TERMINAL_OUTPUT="console" +GRUB_CMDLINE_LINUX="vconsole.keymap=la-latin1 rd.lvm.lv=centos_centos7-2/swap crashkernel=auto vconsole.font=latarcyrheb-sun16 rd.lvm.lv=centos_centos7-2/root rhgb quiet" +GRUB_DISABLE_RECOVERY="true" +``` + +除了在线文档外，你也可以使用下面的命令查阅 GNU GRUB 手册： + +``` +# info grub +``` + +如果你对 `/etc/default/grub` 文件中的可用选项特别感兴趣的话，你可以直接查阅配置一节的帮助文档： + +``` +# info -f grub -n 'Simple configuration' +``` + +使用上述命令，你会发现 `GRUB_TIMEOUT` 用于设置启动画面出现和系统自动开始启动（除非被用户中断）之间的时间。当该变量值为 `-1` 时，除非用户主动做出选择，否则不会开始启动。 + +当同一台机器上安装了多个操作系统或内核后，`GRUB_DEFAULT` 就需要用一个整数来指定 GRUB 启动画面默认选择启动的操作系统或内核条目。我们既可以通过上述启动画查看启动条目列表，也可以使用下面的命令： + +### 在 CentOS 和 openSUSE 系统上 + +``` +# awk -F\' '$1=="menuentry " {print $2}' /boot/grub2/grub.cfg +``` + +### 在 Ubuntu 系统上 + +``` +# awk -F\' '$1=="menuentry " {print $2}' /boot/grub/grub.cfg +``` + +如下图所示的例子中，如果我们想要使用版本为 `3.10.0-123.el7.x86_64` 的内核（第四个条目），我们需要将 `GRUB_DEFAULT` 设置为 `3`（条目从零开始编号），如下所示： + +``` +GRUB_DEFAULT=3 +``` + +![](http://www.tecmint.com/wp-content/uploads/2016/03/Boot-System-with-Old-Kernel-Version.png) +> 使用旧版内核启动系统 + +最后一个需要特别关注的 GRUB 配置变量是 `GRUB_CMDLINE_LINUX`，它是用来给内核传递选项的。我们可以在 [内核变量文件][8] 和 [man 7 bootparam][9] 中找到能够通过 GRUB 传递给内核的选项的详细文档。 + +我的 **CentOS 7** 服务器上当前的选项是： + +``` +GRUB_CMDLINE_LINUX="vconsole.keymap=la-latin1 rd.lvm.lv=centos_centos7-2/swap crashkernel=auto vconsole.font=latarcyrheb-sun16 rd.lvm.lv=centos_centos7-2/root rhgb quiet" +``` +为什么你希望修改默认的内核参数或者传递额外的选项呢？简单来说，在很多情况下，你需要告诉内核某些由内核自身无法判断的硬件参数，或者是覆盖一些内核会检测的值。 + +不久之前，就在我身上发生过这样的事情，当时我在自己已用了 10 年的老笔记本上尝试衍生自 **Slackware** 的 **Vector Linux**。完成安装后，内核并没有检测出我的显卡的正确配置，所以我不得不通过 GRUB 传递修改过的内核选项来让它工作。 + +另外一个例子是当你需要将系统切换到单用户模式以执行维护工作时。为此，你可以直接在 `GRUB_CMDLINE_LINUX` 变量中直接追加 `single` 并重启即可： + +``` +GRUB_CMDLINE_LINUX="vconsole.keymap=la-latin1 rd.lvm.lv=centos_centos7-2/swap crashkernel=auto vconsole.font=latarcyrheb-sun16 rd.lvm.lv=centos_centos7-2/root rhgb quiet single" +``` + +编辑完 `/etc/default/grub` 之后，你需要运行 `update-grub` （在 Ubuntu 上）或者 `grub2-mkconfig -o /boot/grub2/grub.cfg` （在 **CentOS** 和 **openSUSE** 上）命令来更新 `grub.cfg` 文件（否则，改动会在系统启动时丢失）。 + +这条命令会处理早先提到的一些启动配置文件来更新 `grub.cfg` 文件。这种方法可以确保改动持久化，而在启动时刻通过 GRUB 传递的选项仅在当前会话期间有效。 + +### 修复 Linux GRUB 问题 + +如果你安装了第二个操作系统，或者由于人为失误而导致你的 GRUB 配置文件损坏了，依然有一些方法可以让你恢复并能够再次启动系统。 + +在启动画面中按下 `c` 键进入 GRUB 命令行模式（记住，你也可以按下 `e` 键编辑默认启动选项），并可以在 GRUB 提示中输入 `help` 命令获得可用命令： + +![](http://www.tecmint.com/wp-content/uploads/2016/03/Fix-Grub-Issues-in-Linux.png) +> 修复 Linux 的 Grub 配置问题 + +我们将会着重关注 **ls** 命令，它会列出已安装的设备和文件系统，并且我们将会看看它可以查找什么。在下面的图片中，我们可以看到有 4 块硬盘（`hd0` 到 `hd3`）。 + +貌似只有 `hd0` 已经分区了（msdos1 和 msdos2 可以证明，这里的 1 和 2 是分区号，msdos 则是分区方案）。 + +现在我们来看看能否在第一个分区 `hd0`（**msdos1**）上找到 GRUB。这种方法允许我们启动 Linux，并且使用高级工具修复配置文件或者如果有必要的话，干脆重新安装 GRUB： + +``` +# ls (hd0,msdos1)/ +``` + +从高亮区域可以发现，`grub2` 目录就在这个分区： + +![](http://www.tecmint.com/wp-content/uploads/2016/03/Find-Grub-Configuration.png) +> 查找 Grub 配置 + +一旦我们确信了 GRUB 位于 (**hd0, msdos1**)，那就让我们告诉 GRUB 该去哪儿查找它的配置文件并指示它去尝试启动它的菜单： + +``` +set prefix=(hd0,msdos1)/grub2 +set root=(hd0,msdos1) +insmod normal +normal +``` + +![](http://www.tecmint.com/wp-content/uploads/2016/03/Find-and-Launch-Grub-Menu.png) +> 查找并启动 Grub 菜单 + +然后，在 GRUB 菜单中，选择一个条目并按下 **Enter** 键以使用它启动。一旦系统成功启动后，你就可以运行 `grub2-install /dev/sdX` 命令修复问题了（将 `sdX` 改成你想要安装 GRUB 的设备）。然后启动信息将会更新，并且所有相关文件都会得到恢复。 + +``` +# grub2-install /dev/sdX +``` + +其它更加复杂的情景及其修复建议都记录在 [Ubuntu GRUB2 故障排除指南][10] 中。该指南中阐述的概念对于其它发行版也是有效的。 + +### 总结 + +本文向你介绍了 GRUB，并指导你可以在何处找到线上和线下的文档，同时说明了如何面对由于引导加载相关的问题而导致系统无法正常启动的情况。 + +幸运的是，GRUB 是文档支持非常丰富的工具之一，你可以使用我们在文中分享的资源非常轻松地获取已安装的文档或在线文档。 + +你有什么问题或建议吗？请不要犹豫，使用下面的评论框告诉我们吧。我们期待着来自你的回复！ + +-------------------------------------------------------------------------------- + +via: http://www.tecmint.com/configure-and-troubleshoot-grub-boot-loader-linux/ + +作者：[Gabriel Cánepa][a] +译者：[ChrisLeeGit](https://github.com/chrisleegit) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: http://www.tecmint.com/author/gacanepa/ +[1]: http://www.tecmint.com/sed-command-to-create-edit-and-manipulate-files-in-linux/ +[2]: http://www.tecmint.com/installing-network-services-and-configuring-services-at-system-boot/ +[3]: http://www.tecmint.com/linux-boot-process/ +[4]: http://www.tecmint.com/linux-boot-process-and-manage-services/ +[5]: http://www.tecmint.com/best-linux-log-monitoring-and-management-tools/ +[6]: http://www.gnu.org/software/grub/manual/ +[7]: http://askubuntu.com/questions/82140/how-can-i-boot-with-an-older-kernel-version +[8]: https://www.kernel.org/doc/Documentation/kernel-parameters.txt +[9]: http://man7.org/linux/man-pages/man7/bootparam.7.html +[10]: https://help.ubuntu.com/community/Grub2/Troubleshooting