1、重启系统并进入GRUB菜单：重启计算机，当系统启动时，快速按下键盘上的上下方向键↑和↓，使引导程序暂停，选择要编辑的内核版本，然后按“e”键进入编辑模式。

2、编辑启动参数：找到以“linux16”或“linuxEFI”开头的那一行命令，在这一行最后追加“rd.break”参数。

   linux16 /vmlinuz3.10.0229.el7.x86_64 root=/dev/mapper/centosroot ro rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosswap:centos/root rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:rootrhGBvga=0x340 lang=enforcing=0 eni

然后在该行末尾追加空格和“rw init=/bin/bash”，最终结果如下：

   linux16 /vmlinuz3.10.0229.el7.x86_64 root=/dev/mapper/centosroot ro rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm.lv=centos/root:/dev/mapper/centosroot:swap rhgb quiet LANG=zh_CN.UTF8 vga=0x340 rd.br rd.lvm16=centos//dev/mapper/centosroot rw init=/bin/bash

3、挂载文件系统为读写模式：输入以下命令将根文件系统重新挂载为读写模式：

   mount o remount,rw /sysroot

4、切换系统的根信息：通过chroot命令切换到新的系统根目录：

   chroot /sysroot

5、修改密码：在新的系统根目录下，使用passwd命令来修改用户的密码：

   passwd root

注意：由于安全原因，输入的新密码不会显示在屏幕上，你需要输入两次新密码进行确认。

6、退出chroot环境：完成上述操作后，退出chroot环境：

   exit

7、更新SELinux信息：如果系统启用了SELinux，需要更新SELinux信息：

   touch /.autorelabel

8、重新启动系统：重新启动系统以使更改生效：

   exec /sbin/init

Faqs

Q1: 如果忘记当前系统的root密码，如何重置？

A1: 你可以通过重启系统并进入单用户模式或者紧急救援模式（如上文所述），然后使用passwd命令来重置root密码。

Q2: 如果系统没有启用SELinux，还需要执行touch /.autorelabel吗？

A2: 如果系统没有启用SELinux，则不需要执行这一步，这一步主要是为了确保SELinux信息在重启后能够正确更新。