1、请详细描述CentOS系统的启动流程(详细到每个过程系统做了哪些事情)
a,post:加电自检,通电搜索并检查物理设备的状态
b,bootsequeence(BIOS):选择启动顺序
c,bootloader(MBR):加载主引导程序 bootloader,硬盘分区表到内存
d,加载内核kernel
e,只读方式挂载根分区文件系统(rootfs)
f,系统初始化(运行/sbin/init)
g,根据 /etc/inittab 中的启动级别,运行系统初始化脚本 /etc/rc.d/rc.sysinit,打开或关闭对应启动级别下的服务(运行 /etc/rc.d/rcx.d/ 下的脚本)
h,启动终端
2、为运行于虚拟机上的CentOS 6添加一块新硬件,提供两个主分区;
(1) 为硬盘新建两个主分区;并为其安装grub;
(2) 为硬盘的第一个主分区提供内核和ramdisk文件; 为第二个分区提供rootfs;
(3) 为rootfs提供bash、ls、cat程序及所依赖的库文件;
(4) 为grub提供配置文件;
(5) 将新的硬盘设置为第一启动项并能够正常启动目标主机;
[root@server ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x9056db41.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
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 (1-2088, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2088, default 2088): +256M
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (35-2088, default 35):
Using default value 35
Last cylinder, +cylinders or +size{K,M,G} (35-2088, default 2088): +4G
Command (m for help): w
The partition table has been altered!
[root@server ~]# mkfs.ext4 /dev/sdb1;mkfs.ext4 /dev/sdb2
[root@server ~]# mkdir /mnt/{boot,sysroot}
[root@server ~]# mount /dev/sdb1 /mnt/boot/ ; mount /dev/sdb2 /mnt/sysroot/
[root@server ~]# ls /mnt/{boot,sysroot}
[root@server ~]# grub-install –root-directory=/mnt /dev/sdb #复制 GRUB 镜像到 /mnt 的 boot 目录下
[root@server ~]# cp /boot/vmlinuz-2.6.32-431.el6.x86_64 /mnt/boot/
[root@server ~]# cp /boot/initramfs-2.6.32-431.el6.x86_64.img /mnt/boot/
[root@server ~]# vim /mnt/boot/grub/grub.conf #新建一个 grub 配置文件
default=0
timeout=15
title CentOS6.5 homemake
root (hd0,0)
kernel /vmlinuz-2.6.32-431.el6.x86_64 ro root=/dev/sdb2 selinux=0 init=/bin/bash
initrd /initramfs-2.6.32-431.el6.x86_64.img
使用第8题的脚本复制bash、ls、cat响应文件到 rootfs
新建一个虚拟机挂载此虚拟机的sdb磁盘启动
3、制作一个kickstart文件以及一个引导镜像。描述其过程。
####制作 ks 文件的方法
a 通过 system-config-kickstart 生成ks配置文件
b 通过复制已有系统ks配置文件并自定义配置
[root@cent7-server ~]# cp /root/anaconda-ks.cfg myks.cfg #复制root目录下的ks配置文件,修改其中选项
[root@cent7-server ~]# vim myks.cfg
#version=RHEL7
# System authorization information
auth –enableshadow –passalgo=sha512
# Use CDROM installation media
cdrom
# Run the Setup Agent on first boot
firstboot –enable
ignoredisk –only-use=sda
# Keyboard layouts
keyboard –vckeymap=us –xlayouts='us'
# System language
lang en_US.UTF-8
# Network information
network –bootproto=static –device=ens160 –onboot=on –ipv6=auto
network –hostname=localhost.localdomain
# System timezone
timezone China/Beijing –isUtc
# System bootloader configuration
bootloader –location=mbr –boot-drive=sda
# Partition clearing information
clearpart –none –initlabel
part /boot –fstype=ext4 –size=200
part / –fstype=ext4 –size=16000
part /swap –size=1024
repo –name="CentOS" –baseurl=cdrom:sr0 –cost=100
%packages
@base
@core
%end
[root@cent7-server ~]# ksvalidator myks.cfg #检查配置文件语法
#### 制作引导盘
[root@cent7-server ~]# mkdir /media/test-cdrom
[root@cent7-server ~]# mount /dev/cdrom /media/test-cdrom/
mount: /dev/sr0 is write-protected, mounting read-only
[root@cent7-server ~]# mkdir /tmp/test-iso
[root@cent7-server ~]# cd /tmp/test-iso/
[root@cent7-server test-iso]# cp -a -r /media/test-cdrom/isolinux/ .
[root@cent7-server test-iso]# cp ~/myks.cfg .
[root@cent7-server test-iso]# ll
total 8
drwxr-xr-x. 2 root root 4096 Jul 4 2014 isolinux
-rw——-. 1 root root 804 Oct 17 10:03 myks.cfg
[root@cent7-server test-iso]# mkisofs -R -J -T -v –no-emul-boot –boot-load-size 4 –boot-info-table -V "my-test-Cent7-boot" -b isolinux/isolinux.bin -c isolinux/boot.cat -o /root/boot.iso /tmp/test-iso/
4、写一个脚本
(1) 能接受四个参数:start, stop, restart, status
start: 输出“starting 脚本名 finished.”
…
(2) 其它任意参数,均报错退出;
#!/bin/bash # if [ $# -ne 1 ];then echo "Usage: $0 start|stop|restart|status" exit fi case $1 in start) echo "starting $0 finished" ;; stop) echo "stop $0 finished" ;; restart) echo "restart $0 finished" ;; status) echo "$0 status" ;; *) echo "wrong argument" echo "Usage: $0 start|stop|restart|status" ;; esac
5、写一个脚本,判断给定的用户是否登录了当前系统;
(1) 如果登录了,则显示用户登录,脚本终止;
(2) 每3秒钟,查看一次用户是否登录;
#!/bin/bash # if [ $# -ne 1 ];then echo "Usage: $0 username" exit fi while id $1 &> /dev/null ;do if who | grep "\<$1\>" &> /dev/null;then echo "User $1 is online" exit else sleep 3 echo "User $1 is offline" fi done
6、写一个脚本,显示用户选定要查看的信息;
cpu) display cpu info
mem) display memory info
disk) display disk info
quit) quit
非此四项选择,则提示错误,并要求用户重新选择,只到其给出正确的选择为止;
#!/bin/bash # while true;do read -p "input your select: cpu|mem|disk|quit " text case $text in cpu) cat /proc/cpuinfo && exit;; mem) free -m && exit;; disk) df -h && exit;; quit) exit ;; *) echo "wrong choice" continue ;; esac done
7、写一个脚本
(1) 用函数实现返回一个用户的UID和SHELL;用户名通过参数传递而来;
(2) 提示用户输入一个用户名或输入“quit”退出;
当输入的是用户名,则调用函数显示用户信息;
当用户输入quit,则退出脚本;进一步地:显示键入的用户相关信息后,再次提醒输出用户名或quit:
#!/bin/bash # UserInfo () { id -u $username sed -n "/\<$username\>/p" /etc/passwd | awk -F: '{print $7}' } while true;do read -p "pls input username: " username if [ -z "$username" ];then echo "you must input username" exit fi if id $username &> /dev/null;then UserInfo $username continue elif [ "$username" == "quit" ];then exit else echo "invaild username" fi done
8、写一个脚本,完成如下功能(使用函数)
(1) 提示用户输入一个可执行命令的名字;获取此命令依赖的所有库文件;
(2) 复制命令文件至/mnt/sysroot目录下的对应的rootfs的路径上,例如,如果复制的文件原路径是/usr/bin/useradd,则复制到/mnt/sysroot/usr/bin/目录中;
(3) 复制此命令依赖的各库文件至/mnt/sysroot目录下的对应的rootfs的路径上;规则同上面命令相关的要求;
#!/bin/bash # Judge () { if [ -z "$cmd" ] || ! which $cmd &> /dev/null ;then echo "wrong command!" exit fi } Copy_cmd () { [ ! -d $cmd_dir ] && mkdir -p $cmd_dir &> /dev/null cp $(which $cmd) $cmd_dir } Copy_lib () { echo $lib_path mkdir -p /mnt/sysroot/lib{,64} for list in $lib_path;do cp $list /mnt/sysroot$list done } read -p "pls input an executable command: " cmd cmd_path=$(which $cmd | grep -o "^/.*\/") cmd_dir=/mnt/sysroot$(dirname $(which $cmd)) lib_path=$(ldd $(which $cmd) | grep -o "/[^[:space:]]\{1,\}") Judge Copy_cmd Copy_lib
原创文章,作者:Net21_木头,如若转载,请注明出处:http://www.178linux.com/47488
评论列表(1条)
开机启动流程 如果能用图来说明就更好了,还有你的每一条命令,如果是为同一问题的答案,可以用“代码”美化一下