制作一个只运行bash的系统及破坏mbr表并修复

制作一个只运行bash的系统

1、新增一块硬盘，分三个区。

分区1：boot目录100M

分区2：2G，swap分区

分区3：5G，根目录。

其中分区1、3格式化为ext4文件系统，分区2格式化为swap。

2、/mnt下新建两个目录boot和sysroot。

分区1挂载至boot目录，分区3挂载至sysroot目录

grub安装至分区1，复制内核和initramfs至boot目录

[[email protected] ~]# mount /dev/sdb1 /mnt/boot

[[email protected] ~]# ls /mnt/boot

lost+found

[[email protected] ~]# grub-install --root-directory=/mnt /dev/sdb

#安装grub至新增的sdb硬盘，指明目录--root-directory为/mnt目录，grub会自动寻找boot目录

#指明安装的硬盘/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

[[email protected] ~]# cp /boot/vmlinuz-2.6.32-696.el6.x86_64 /mnt/boot/vmlinuz

[[email protected] ~]# cp /boot/initramfs-2.6.32-696.el6.x86_64.img /mnt/boot/initramfs.img

# 复制vmlinuz文件和intramfs.img文件至新硬盘boot目录

[[email protected] ~]# ls /mnt/boot

grub  initramfs.img  lost+found  vmlinuz

[[email protected] ~]# vim /mnt/boot/grub/grub.conf

[[email protected] ~]# cat /mnt/boot/grub/grub.conf #在grub目录下创建grub.conf文件，增加内容

default=0

timeout=5

title Centos64 (mylinux)

root (hd0,0)

kernel /vmlinuz selinux=0 ro root=/dev/sda3 init=/bin/bash #kernel的路径和根目录的路径

initrd /initramfs.img

[[email protected] ~]# mount /dev/sdb3 /mnt/sysroot

[[email protected] ~]# ls /mnt/sysroot

lost+found

[[email protected] ~]# cd /mnt/sysroot/

[[email protected] sysroot]# mkdir -pv etc bin sbin lib lib64 dev proc sys tmp usr home root mnt media

# 创建根文件系统

mkdir: 已创建目录 "etc"

mkdir: 已创建目录 "bin"

mkdir: 已创建目录 "sbin"

mkdir: 已创建目录 "lib"

mkdir: 已创建目录 "lib64"

mkdir: 已创建目录 "dev"

mkdir: 已创建目录 "proc"

mkdir: 已创建目录 "sys"

mkdir: 已创建目录 "tmp"

mkdir: 已创建目录 "usr"

mkdir: 已创建目录 "home"

mkdir: 已创建目录 "root"

mkdir: 已创建目录 "mnt"

mkdir: 已创建目录 "media"

[[email protected] sysroot]# ls

bin  dev  etc  home  lib  lib64  lost+found  media  mnt  proc  root  sbin  sys  tmp  usr

[[email protected] sysroot]# cp /bin/bash ./bin/ #复制bash程序至新硬盘，目录要与原bash路径一致

[[email protected] sysroot]# ls ./bin/

bash

[[email protected] sysroot]# ldd /bin/bash #查看bash所依赖的库，并复制到新硬盘对应目录下

linux-vdso.so.1 =>  (0x00007fff2b3f4000)

libtinfo.so.5 => /lib64/libtinfo.so.5 (0x0000003532a00000)

libdl.so.2 => /lib64/libdl.so.2 (0x0000003530a00000)

libc.so.6 => /lib64/libc.so.6 (0x0000003530600000)

/lib64/ld-linux-x86-64.so.2 (0x0000003530200000)

[[email protected] sysroot]# cd /lib64

[[email protected] lib64]# cp libtinfo.so.5 libdl.so.2 libc.so.6 ld-linux-x86-64.so.2 /mnt/sysroot/lib64

[[email protected] lib64]# ls /mnt/sysroot/lib64

ld-linux-x86-64.so.2  libc.so.6  libdl.so.2  libtinfo.so.5

[[email protected] lib64]# chroot /mnt/sysroot/ #测试bash是否正常

bash-4.1# type type #bash内置命令可用，外置命令不可用。

type is a shell builtin

bash-4.1# type cat

bash: type: cat: not found

bash-4.1# exit

exit

[[email protected] lib64]# init 0

找到刚刚添加的硬盘的路径，新创建一个虚拟机使用刚才添加的硬盘。

添加完成后即可启动系统进入bash

破坏mbr表并修复：

方法一：磁盘中可以没有boot目录

[[email protected] ~]# dd if=/dev/sda of=/root/mbr.bak count=1 bs=512 #备份mbr表

1+0 records in

1+0 records out

512 bytes (512 B) copied, 0.000419863 s, 1.2 MB/s

[[email protected] ~]# dd if=/dev/zero of=/dev/sda count=1 bs=200 #破坏mbr表前200字节

1+0 records in

1+0 records out

200 bytes (200 B) copied, 0.000233899 s, 855 kB/s

[[email protected] ~]# sync #把刚才的操作同步至磁盘

[[email protected] ~]# grub-install --root-directory=/ /dev/sda #安装新的

Installation finished. No error reported.

This is the contents of the device map //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'.

# this device map was generated by anaconda

(hd0)     /dev/sda

方法二：磁盘中要有boot目录，并且包含stage1，stage1_5，stage2文件

[[email protected] ~]# dd if=/dev/zero of=/dev/sda count=1 bs=200

1+0 records in

1+0 records out

200 bytes (200 B) copied, 0.000163216 s, 1.2 MB/s

[[email protected] ~]# sync

[[email protected] ~]# grub

Probing devices to guess BIOS drives. This may take a long time.

GNU GRUB  version 0.97  (640K lower / 3072K upper memory)

[ Minimal BASH-like line editing is supported.  For the first word, TAB

lists possible command completions.  Anywhere else TAB lists the possible

completions of a device/filename.]

grub> root (hd0,0) #指明根所在的分区

root (hd0,0)

Filesystem type is ext2fs, partition type 0x83

grub> setup (hd0) #指明安装的磁盘

setup (hd0)

Checking if "/boot/grub/stage1" exists... no

Checking if "/grub/stage1" exists... yes

Checking if "/grub/stage2" exists... yes

Checking if "/grub/e2fs_stage1_5" exists... yes

Running "embed /grub/e2fs_stage1_5 (hd0)"...  27 sectors are embedded.

succeeded

Running "install /grub/stage1 (hd0) (hd0)1+27 p (hd0,0)/grub/stage2 /grub/grub.conf"... succeeded

Done.

grub> quit

quit

[[email protected] ~]# sync

方法三：光盘引修复

bash-4.1# chroot /mnt/sysimage/

sh-4.1# ls #查看系统中的文件

sh-4.1# grub-install --root-directory=/ /dev/sda #安装mbr

原文地址：http://blog.51cto.com/11975865/2063367