CentOS 6系统/boot分区被删除了，但是又不想重新安装系统，下面介绍一种快速的方法恢复boot分区。
1.首先利用centos6镜像进入linux rescue救援模式。
2.启动sshd服务，查看eth0获取的ip地址,然后用ssh secure shell 连接。
SSH Secure Shell 3.2.9 (Build 283)
Copyright (c) 2000-2003 SSH Communications Security Corp - http://www.ssh.com/
This copy of SSH Secure Shell is a non-commercial version.
This version does not include PKI and PKCS #11 functionality.
[root@localhost ~]# cd /boot //进入/boot分区
[root@localhost boot]# ls //查看boot分区的内容
config-2.6.32-71.el6.i686 symvers-2.6.32-71.el6.i686.gz
grub System.map-2.6.32-71.el6.i686
initramfs-2.6.32-71.el6.i686.img vmlinuz-2.6.32-71.el6.i686
[root@localhost boot]# cd ..//返回上层目录
[root@localhost /]# rm -rf /boot/*//删除/boot分区所有内容
[root@localhost /]# ls /boot//查看/boot分区内容为空
[root@localhost /]# mount /dev/sr0 /mnt//挂载cdrom设备到/mnt目录下
mount: block device /dev/sr0 is write-protected, mounting read-only
[root@localhost /]# rpm -ivh /mnt/Packages/kernel-2.6.32-71.el6.i686.rpm --root=/ --force //安装光盘的kernel软件包
Preparing... ################## [100%]
1:kernel ################### [100%]
[root@localhost /]# ls /boot //查看/boot分区内容
config-2.6.32-71.el6.i686 System.map-2.6.32-71.el6.i686
initramfs-2.6.32-71.el6.i686.img vmlinuz-2.6.32-71.el6.i686
symvers-2.6.32-71.el6.i686.gz
[root@localhost /]# mkdir /boot/grub//在/boot目录新建一个grub目录
[root@localhost /]# touch /boot/grub/grub.conf//新建一个grub.conf配置文件
[root@localhost /]# cp -rf /usr/share/grub/i386-pc/* /boot/grub/ //把/usr/share/grub/i386-pc的所有内容拷贝到/boot/grub中。
[root@localhost /]# ls /boot//查看/boot分区内容
config-2.6.32-71.el6.i686 symvers-2.6.32-71.el6.i686.gz
grub System.map-2.6.32-71.el6.i686
initramfs-2.6.32-71.el6.i686.img vmlinuz-2.6.32-71.el6.i686
[root@localhost /]# ls /boot/grub/ //查看/boot/grub目录内容
e2fs_stage1_5 iso9660_stage1_5 stage1 vstafs_stage1_5
fat_stage1_5 jfs_stage1_5 stage2 xfs_stage1_5
ffs_stage1_5 minix_stage1_5 stage2_eltorito
grub.conf reiserfs_stage1_5 ufs2_stage1_5
[root@localhost /]# fdisk -l //查看分区
Disk /dev/sda: 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: 0x000b1db4
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 102400 83 Linux//这个为/boot启动分区
Partition 1 does not end on cylinder boundary.
/dev/sda2 13 144 1048576 82 Linux swap / Solaris
Partition 2 does not end on cylinder boundary.
/dev/sda3 144 2611 19819520 83 Linux //这个为/根分区
[root@localhost /]# mount//查看所有挂载分区
/dev/sda3 on / type ext4 (rw)//根分区
/dev/sda1 on /boot type ext4 (rw)//boot分区为sda1
devpts on /dev/pts type devpts (rw)
tmpfs on /dev/shm type tmpfs (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
/dev/sr0 on /mnt type iso9660 (ro)
[root@localhost /]# grub//启动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) //首先find /grub/stage1查看/boot分区为(hd0,0)
root (hd0,0)//设置/boot分区为/dev/sda1
Filesystem type is ext2fs, partition type 0x83
grub> setup (hd0)//重新安装grub
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)"... 26 sectors are embedded.
succeeded
Running "install /grub/stage1 (hd0) (hd0)1+26 p (hd0,0)/grub/stage2 /grub/grub.conf"... succeeded
Done.
grub> quit//退出
3.重新reboot启动系统进入grub界面测试
4.查找find /grub/stage1然后找到/boot分区为(hd0,0),指定kernel，initrd, boot启动系统成功。
5.系统启动成功，然后进入系统重新写/boot/grub/grub.conf文件。
6.[root@localhost /]# vi /boot/grub/grub.conf配置文件如下：
最后填写grub.conf文件内容
default=0 //默认菜单为第一个
timeout=6//等待时间为6秒
title mylinux //启动标题为mylinux
root (hd0,0) //boot所在分区为/dev/sda1
kernel /vmlinuz-2.6.32-71.el6.i686 ro root=/dev/sda3 rhgb quiet//kernel所在位置以只读模式挂载/dev/sda3根分区rhgb quiet为安静模式不显示内核信息。
initrd /initramfs-2.6.32-71.el6.i686.img//加载initrd镜像。
7.最后进入linux rescue重建一个grub
8.最后启动界面看是否成功了。