内容:

1、linux系统启动排错及恢复(救援模式的使用)

2、自制linux系统

3、编译linux内核


一、系统启动排错及恢复(救援模式的使用)

    1、bootloader损坏恢复

        (1)进入救援模式

        (2)在shell中运行grub程序

sh 3.1#grub
grub>root (hdx,y)
grub>setup (hd0) # setup (hd0)就是把GRUB写到硬盘的MBR上。
grub>quit

    

        这里的X,如果是一个盘,就是0,如果你所安装的linux的根分区在第二个硬盘上,那X就是1了;Y,就是装有linux系统所在的根分区。


        总结:在rescue模式下可以重装GRUB引导程序,修复MBR扇区。

[16:54 root@Centos6.8~]# dd if=/dev/zero of=/dev/sda bs=30 count=1
1+0 records in
1+0 records out
30 bytes (30 B) copied, 0.00292207 s, 10.3 kB/s
[18:44 root@Centos6.8~]# reboot now

    

wKiom1fWg7uiX5JbAAA5K8-_YWQ199.png


    成功修复:

wKioL1fWg7uhW_hrAAAGPZz7938569.png

 

       2、vmlinux内核损坏恢复

        (1)删除kernel做实验,要加上--nodeps:忽略依赖关系

        (2)开机进入救援模式

        (3)把光盘挂载上(内核文件在光盘里),注意,不要把光盘直接挂载在/mnt下,会把真根系统给隐藏了

        (4)rpm安装kernel包,注意,救援模式下的真正的根是在/mnt/sysp_w_picpath下,所以rpm要加上选项--root=/mnt/sysp_w_picpath(如果切换了根chroot,则不需要此参数)

        (5)重启后恢复系统

[19:22 root@Centos6.8~]# rpm -q kernel
kernel-2.6.32-642.el6.x86_64
[19:31 root@Centos6.8~]# rpm -e kernel
error: Failed dependencies:
kernel >= 2.6.30 is needed by (installed) pulseaudio-0.9.21-24.el6.x86_64
kernel >= 2.6.17 is needed by (installed) autofs-1:5.0.5-122.el6.x86_64
kernel >= 2.6.14 is needed by (installed) fuse-2.8.3-5.el6.x86_64
kernel >= 2.6.32-33.el6 is needed by (installed) xorg-x11-drv-intel-2.99.917-0.4.20151111.el6.x86_64
kernel >= 2.6.32-33.el6 is needed by (installed) xorg-x11-drv-ati-7.6.1-2.el6.x86_64
kernel >= 2.6.32-358.2.1 is needed by (installed) irqbalance-2:1.0.7-8.el6.x86_64
kernel >= 2.6.12-1.1411_FC5 is needed by (installed) pcmciautils-015-4.2.el6.x86_64
kernel-drm-nouveau = 16 is needed by (installed) xorg-x11-drv-nouveau-1:1.0.12-1.el6.x86_64
[19:31 root@Centos6.8~]# rpm -e kernel --nodeps
grubby fatal error: unable to find a suitable template
grubby: doing this would leave no kernel entries. Not writing out new config.
warning:    erase unlink of /lib/modules/2.6.32-642.el6.x86_64/weak-updates failed: No such file or directory
warning:    erase unlink of /lib/modules/2.6.32-642.el6.x86_64/modules.order failed: No such file or directory
warning:    erase unlink of /lib/modules/2.6.32-642.el6.x86_64/modules.networking failed: No such file or directory
warning:    erase unlink of /lib/modules/2.6.32-642.el6.x86_64/modules.modesetting failed: No such file or directory
warning:    erase unlink of /lib/modules/2.6.32-642.el6.x86_64/modules.drm failed: No such file or directory
warnin g:    erase unlink of /lib/modules/2.6.32-642.el6.x86_64/modules.block failed: No such file or directory



无法进入系统:

wKioL1fSvZrwUzbbAAAE1afs_gQ818.png



进入救援模式:

wKiom1fSvU-hfYV2AAAKYNWLG-0967.png



安装kernel:

wKiom1fSvbjCB0yNAABTVRnqDk0426.png



成功修复:

wKioL1fSvdGRsiOgAABqiQy69sc389.png



3、initramfs文件损坏恢复

        (1)把initramfs文件删除,模拟initramfs文件损坏

        (2)进入救援模式,chroot=/mnt/sysp_w_picpath,再使用mkinitrd命令重新生成initramfs文件【注意,一定要在boot目录下使用该命令】

        (3)重启即可

[19:58 root@Centos6.8/boot]# rm -f initramfs-2.6.32-642.el6.x86_64.img 
[19:58 root@Centos6.8/boot]# reboot
Broadcast message from root@Centos6.8
(/dev/pts/0) at 19:58 ...
The system is going down for reboot NOW!
sh 3.1# mkinitrd /boot/initramfs-`uname -r`.img `uname -r`


        4、/etc/fstab文件损坏恢复

        (1)进入救援模式

        (2)知道根在哪个分区就是直接把根挂载上,然后修改fstab文件,如果不知道根在哪个分区则需要逐一尝试挂载,直到找到根系统,然后修改fstab文件

        (3)修改完后重启即可

[19:14 root@Centos6.8~]# rm -f /etc/fstab 
[19:15 root@Centos6.8~]# reboot 
Broadcast message from root@Centos6.8
(/dev/pts/0) at 19:15 ...
The system is going down for reboot NOW!


    5、/boot目录文件误删除恢复

        (1)挂载光盘

        (2)安装kernel rpm -ivh --force(会同时生成initramfs)

        (3)安装grub:grub-install (必须切换到真根目录运行该命令),但是没有grub.conf文件需要手动创建


总结:把boot分区删掉,实际是删除了kernel和grub,所以把kernel和grub安装上去即可,同时需要手工配置grub.conf文件


[19:22 root@Centos6.8/]# rm -rf /boot/
rm: cannot remove `/boot': Device or resource busy
[19:22 root@Centos6.8/]# ls /boot/
[19:22 root@Centos6.8/]# ls /boot/
[19:22 root@Centos6.8/]# ll /boot/
total 0



挂载光盘:

wKiom1fSvlSz9fHMAAAiPNkvbVo460.png


安装kernel:

wKioL1fSvnjyYI09AAANnCiNonE176.png


安装grub(需要切换到真根):

wKiom1fSvrjx4rMSAAASyxfwTYw329.png

wKiom1fSvrmQoCvEAAAeYLCq97E815.png



更多内容请关注我的博客

二、自制linux系统

步骤概述:

    1、新建一个硬盘

    2、在该新硬盘上新建两个分区,一个当boot分区,一个当/分区 

    3、格式化并且挂载两个分区,注意,其中boot分区的挂载目录一定是boot名字的目录

    4、在新硬盘安装grub(要使用--root-directory参数指定新硬盘的根分区),同时手动配置grub.conf配置文件

    5、把kernel和initramfs文件放置boot分区

    6、在根分区创建相应的目录

    7、把一些常用命令拷贝至新硬盘的根分区,注意,同时要把二进制程序相应的库文件一并拷到新硬盘的lib文件夹(这里更加加深了二进制程序和库文件的关系,可以把库文件理解成二进制程序的函数)

    8、把硬盘拆下,安装到新的虚拟机测试

步骤演示详解过程:

    1、新建一个硬盘

    2、在该新硬盘上新建两个分区,一个当boot分区,一个当/分区

[20:00 root@Centos6.8~]# fdisk /dev/sdb
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').
Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2610, default 1): 
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): +100M
Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (15-2610, default 15): 
Using default value 15
Last cylinder, +cylinders or +size{K,M,G} (15-2610, default 2610): +1G
Command (m for help): p
Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xefd94e53
   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1          14      112423+  83  Linux
/dev/sdb2              15         146     1060290   83  Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[20:01 root@Centos6.8~]# lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sr0     11:0    1   3.7G  0 rom  
sda      8:0    0   200G  0 disk 
├─sda1   8:1    0   200M  0 part /boot
├─sda2   8:2    0  48.8G  0 part /
├─sda3   8:3    0  19.5G  0 part /testdir
├─sda4   8:4    0     1K  0 part 
└─sda5   8:5    0   3.9G  0 part [SWAP]
sdb      8:16   0    20G  0 disk 
├─sdb1   8:17   0 109.8M  0 part 
└─sdb2   8:18   0     1G  0 part


    3、格式化并且挂载两个分区,注意,其中boot分区的挂载目录一定是boot名字的目录

[20:04 root@Centos6.8~]# mkfs.ext4 /dev/sdb1
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
28112 inodes, 112420 blocks
5621 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
14 block groups
8192 blocks per group, 8192 fragments per group
2008 inodes per group
Superblock backups stored on blocks: 
8193, 24577, 40961, 57345, 73729
Writing inode tables: done                            
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 22 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
[20:05 root@Centos6.8~]# mkfs.ext4 /dev/sdb2
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
66384 inodes, 265072 blocks
13253 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=272629760
9 block groups
32768 blocks per group, 32768 fragments per group
7376 inodes per group
Superblock backups stored on blocks: 
32768, 98304, 163840, 229376
Writing inode tables: done                            
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 27 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
[20:05 root@Centos6.8~]# mkdir /mnt/boot
[20:05 root@Centos6.8~]# mkdir /mnt/root
[20:05 root@Centos6.8~]# mount /dev//sdb1 /mnt/boot/
[20:05 root@Centos6.8~]# mount /dev//sdb2 /mnt/root/
[20:05 root@Centos6.8~]# df
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/sda2       50264772 5723488  41981284  12% /
tmpfs            1019184       0   1019184   0% /dev/shm
/dev/sda1         194241   33869    150132  19% /boot
/dev/sda3       20027260   44996  18958264   1% /testdir
/dev/sdb1         104769    1550     97598   2% /mnt/boot
/dev/sdb2        1010812    1304    956496   1% /mnt/root


    4、在新硬盘安装grub,同时手动配置grub.conf配置文件

[20:08 root@Centos6.8/mnt/boot]# ls
lost+found
[20:08 root@Centos6.8/mnt/boot]# ll
total 12
drwx------. 2 root root 12288 Sep  9 20:05 lost+found
[20:09 root@Centos6.8/mnt/boot]# grub-install --root-directory=/mnt /dev/sdb
Probing devices to guess BIOS drives. This may take a long time.
Installation finished. No error reported.
This is the contents of the device map /mnt/boot/grub/device.map.
Check if this is correct or not. If any of the lines is incorrect,
fix it and re-run the script `grub-install'.
(fd0)/dev/fd0
(hd0)/dev/sda
(hd1)/dev/sdb
[20:10 root@Centos6.8/mnt/boot]# ll
total 14
drwxr-xr-x. 2 root root  1024 Sep  9 20:10 grub
drwx------. 2 root root 12288 Sep  9 20:05 lost+found
[20:34 root@Centos6.8/mnt/root/lib]# cat !$
cat /mnt/boot/grub/grub.conf
default=0
timeout=5
title YOUR LINUX
root(hd0,0)
kernel /initramfs-2.6.32-642.el6.x86_64.img root=/dev/sda2 init=/bin/bash
initrd /vmlinuz-2.6.32-642.el6.x86_64

    5、把kernel和initramfs文件放置boot分区

[20:10 root@Centos6.8/mnt/boot]# cp /boot/vmlinuz-2.6.32-642.el6.x86_64 /boot/initramfs-2.6.32-642.el6.x86_64.img .
[20:17 root@Centos6.8/mnt/boot]# ls
grub  initramfs-2.6.32-642.el6.x86_64.img  lost+found  vmlinuz-2.6.32-642.el6.x86_64

    6、在根分区创建相应的目录

[20:17 root@Centos6.8/mnt/boot]# cd /mnt/root/
[20:18 root@Centos6.8/mnt/root]# ls
lost+found
[20:18 root@Centos6.8/mnt/root]# mkdir {etc,home,lib,lib64,usr,proc,sys,mnt,media,var,root,bin,sbin,tmp,dev}
[20:20 root@Centos6.8/mnt/root]# ls
bin  dev  etc  home  lib  lib64  lost+found  media  mnt  proc  root  sbin  sys  tmp  usr  var

    7、把一些常用命令拷贝至新硬盘的根分区,注意,同时要把二进制程序相应的库文件一并拷到新硬盘的lib文件夹(这里更加加深了二进制程序和库文件的关系,可以把库文件理解成二进制程序的函数)

这里写了一个脚本来进行复制:

#!/bin/bash
 
ch_root="/mnt/root"
[ ! -d $ch_root ] && mkdir $ch_root
 
bincopy() {
    if which $1 &>/dev/null; then
        local cmd_path=`which --skip-alias $1`
        local bin_dir=`dirname $cmd_path`
        [ -d ${ch_root}${bin_dir} ] || mkdir -p ${ch_root}${bin_dir}
        [ -f ${ch_root}${cmd_path} ] || cp $cmd_path ${ch_root}${bin_dir}
        return 0
    else
        echo "Command not found."
        return 1
    fi
}
 
libcopy() {
    local lib_list=$(ldd `which --skip-alias $1` | grep -Eo '/[^[:space:]]+')
    for loop in $lib_list;do
        local lib_dir=`dirname $loop`
        [ -d ${ch_root}${lib_dir} ] || mkdir -p  ${ch_root}${lib_dir}
        [ -f ${ch_root}${loop} ] || cp $loop ${ch_root}${lib_dir}
    done
}
 
 
read -p "Please input a command or quit: " command
 
while [ "$command" != "quit" ];do
    if bincopy $command ;then
        libcopy $command
    fi
    read -p "Please input a command or quit: " command
done
[20:44 root@Centos6.8/mnt/root/etc]# tree /mnt/root/
/mnt/root/
├── bin
│   ├── bash
│   ├── df
│   ├── echo
│   ├── ls
│   ├── lsblk
│   └── mount
├── dev
├── etc
│   └── fstab
├── home
├── lib
│   ├── ld-linux-x86-64.so.2
│   ├── libacl.so.1
│   ├── libattr.so.1
│   ├── libblkid.so.1
│   ├── libcap.so.2
│   ├── libc.so.6
│   ├── libdl.so.2
│   ├── libpthread.so.0
│   ├── librt.so.1
│   ├── libselinux.so.1
│   ├── libsepol.so.1
│   ├── libtinfo.so.5
│   └── libuuid.so.1
├── lib64
├── lost+found
├── media
├── mnt
├── proc
├── root
├── sbin
├── sys
├── tmp
├── usr
└── var


    8、把硬盘拆下,安装到新的虚拟机测试


三、编译linux内核

    1、为什么需要编译内核

编译内核可能是出于某种需求,比如对内核大小有要求,去掉内核中某些用不到的部分,或者添加一些自己需要的部分,如ntfs文件系统,或者自己修改了某部分内核代码,需要编译后验证功能。

    2、编译内核步骤

    (1)到kernel.org下载需要编译的版本的内核源码包

    (2)准备相应的开发编译环境:包组(CentOS 6):

        Server Platform Development

        Development Tools

    (2)把kernel拷贝到/usr/src目录下,并且解压放在linux的目录(一般编译会再/usr/src/linux目录进行,放在其他目录也可以)

[12:16 root@Centos6.8/usr/src]# ll
total 71504
drwxr-xr-x.  2 root root     4096 Sep 23  2011 debug
drwxr-xr-x.  3 root root     4096 Aug 26 19:03 kernels
drwxrwxr-x. 23 root root     4096 Aug 29 21:50 linux
-rw-r--r--.  1 root root 73207156 Aug 30  2013 linux-3.10.10.tar.xz


    (3)进入/usr/src/linux目录,注意,一定要进入该目录,运行字符界面的模块选择界面命令make menuconfig,然后按需要选择需要的功能即可

[12:19 root@Centos6.8/usr/src/linux]# make menuconfig
 .config - Linux/x86 3.10.10 Kernel Configuration
 qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq
  lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq Linux/x86 3.10.10 Kernel Configuration qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqk
  x  Arrow keys navigate the menu.  <Enter> selects submenus --->.  Highlighted letters are hotkeys.  Pressing <Y> includes, <N>  x  
  x  excludes, <M> modularizes features.  Press <Esc><Esc> to exit, <?> for Help, </> for Search.  Legend: [*] built-in  [ ]      x  
  x  excluded  <M> module  < > module capable                                                                                     x  
  x                                                                                                                               x  
  x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqk x  
  x x                          [*] 64-bit kernel                                                                                x x  
  x x                              General setup  --->                                                                          x x  
  x x                          [*] Enable loadable module support  --->                                                         x x  
  x x                          -*- Enable the block layer  --->                                                                 x x  
  x x                              Processor type and features  --->                                                            x x  
  x x                              Power management and ACPI options  --->                                                      x x  
  x x                              Bus options (PCI etc.)  --->                                                                 x x  
  x x                              Executable file formats / Emulations  --->                                                   x x  
  x x                          -*- Networking support  --->                                                                     x x  
  x x                              Device Drivers  --->                                                                         x x  
  x x                              Firmware Drivers  --->                                                                       x x  
  x x                              File systems  --->                                                                           x x  
  x x                              Kernel hacking  --->                                                                         x x  
  x x                              Security options  --->                                                                       x x  
  x x                          -*- Cryptographic API  --->                                                                      x x  
  x x                          [*] Virtualization  --->                                                                         x x  
  x x                              Library routines  --->                                                                       x x  
  x mqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj x  
  tqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqu  
  x                                   <Select>    < Exit >    < Help >    < Save >    < Load >                                    x  
  mqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj

                                                                                                                                     

    (4)保存好编译模块后,就可以进行内核的编译了(注意,请预留至少10G的空间,在编译的过程中会产生很多临时文件,同时编译时间长短根据机器性能决定)

        make [-j #] :#表示多少个CPU进行编译

        make modules_install:安装模块

        make install :安装内核相关文件

        重启

重启系统后即可看见编译的内核

wKiom1fWgxbjoD7-AAB397Mpmzw724.png

wKiom1fWgxfBeAc_AACHsknPPuc872.png


OK,更多内容请关注我的博客