济南正规企业站seo,购买服务器做网站,深圳品牌沙发,wordpress页面排版插件目录 1 C entOS 6 的启动管理1.1 Linux 组成1.2 内核设计流派1.3 CentOS 6启动流程1.3.1 CentOs 6 启动流程1.3.1 硬件启动POST1.3.2 bootloader 启动/引导加载器1.3.2.1 grub 功能和组成1.3.2.2 CentOS 6 grub 安装1.3.2.3 grub legacy 管理 1.3.3 加载 kernel1.3.4 init 初始… 目录 1 C entOS 6 的启动管理1.1 Linux 组成1.2 内核设计流派1.3 CentOS 6启动流程1.3.1 CentOs 6 启动流程1.3.1 硬件启动POST1.3.2 bootloader 启动/引导加载器1.3.2.1 grub 功能和组成1.3.2.2 CentOS 6 grub 安装1.3.2.3 grub legacy 管理 1.3.3 加载 kernel1.3.4 init 初始化1.3.4.1 运行级别1.3.4.2 初始化脚本 sysinit1.3.4.3 服务管理1.3.4.4 非独立服务1.3.4.5 开机启动文件 rc.local 1.3.5 Centos 启动过程总结 1.4 自制linux系统1.4.0为当前Linux系统增加硬盘1.4.1 分区并创建文件系统1.4.2 挂载boot1.4.3 安装grub1.4.4 准备内核和initramfs文件1.4.5 手动建立grub.conf1.4.6 准备根下面相关程序和库1.4.7 准备新的虚拟机 1.5 启动过程的故障排错1.5.1 实战案例1.5.2 实战案例 2 /proc 目录和内核参数管理3 /sys 目录4 内核模块管理和编译4.1 内核版本4.2 内核模块命令4.3 编译内核4.3.1 编译准备4.3.1.1.目标主机硬件设备相关信息4.3.1.2 开发环境相关包4.3.1.3 内核编译安装实现4.3.1.4 编译安装内核实战案例4.3.1.4 内核编译说明4.3.1.5 卸载内核 5 Busybox5.1 Busybox介绍5.2 Busybox使用5.3 busybox编译安装 6 systemd6.1 systemd 特性6.2 systemctl管理系统服务service unit6.3 service unit文件格式6.4 运行级别6.5 Centos 7之后版本引导顺序6.6 设置内核参数6.7 破解 CentOS 7和8的 root 密码6.8 实现GRUB2安全6.9 修复GRUB26.10 故障排错实战案例6.10.1 实战案例1: centos 78 破坏MBR后进行恢复6.10.2 实战案例2: entos 78删除/boot/grub2/*所有内容进行恢复6.10.3 实战案例3: Centos 78 删除/boot/下所有文件后进行恢复 1 C entOS 6 的启动管理
1.1 Linux 组成 kernel 实现进程管理、内存管理、网络管理、驱动程序、文件系统、安全功能等功能 rootfs 包括程序和 glibc 库 程序:二进制执行文件 库: 函数集合function 调用接口 (头文件负责描述)
1.2 内核设计流派 宏内核(monolithic kernel): 又称单内核和强内核UnixLinux 把所有系统服务都放到内核里所有功能集成于同一个程序分层实现不同功能系统庞大复杂Linux其实在单内核内核实现了模块化也就相当于吸收了微内核的优点 微内核(micro kernel): WindowsSolarisHarmonyOS 简化内核功能在内核之外的用户态尽可能多地实现系统服务同时加入相互之间的安全保护每种功能使用一个单独子系统实现将内核功能移到用户空间性能差
1.3 CentOS 6启动流程
1.3.1 CentOs 6 启动流程 加载BIOS的硬件信息获取第一个启动设备读取第一个启动设备MBR的引导加载程序(grub)的启动信息加载核心操作系统的核心信息核心开始解压缩并尝试驱动所有的硬件设备核心执行init程序并获取默认的运行信息init程序执行/etc/rc.d/rc.sysinit文件重新挂载根文件系统启动核心的外挂模块init执行运行的各个批处理文件(scripts)init执行/etc/rc.d/rc.local执行/bin/login程序等待用户登录登录之后开始以shell控制主机
1.3.1 硬件启动POST
POSTPower-On-Self-Test加电自检是BIOS功能的一个主要部分。负责完成对CPU、主板、内存、硬盘子系统、显示子系统、串并行接口、键盘等硬件情况的检测
主板的ROMBIOSBasic lnput and Output System 基本输入输出系统保存着有关计算机系统最重要的基本输入输出程序系统信息设置、开机加电自检程序和系统启动自举程序等
主板的RAMCMOS 互补金属氧化物半导体保存各项参数的设定按次序查找引导设备第一个有引导程序的设备为本次启动设备
1.3.2 bootloader 启动/引导加载器
1.3.2.1 grub 功能和组成
bootloader引导加载器引导程序
windowsntloader仅是启动OSLinux功能丰富提供菜单允许用户选择要启动系统或不同的内核版本把用户选定的内核装载到内存中的特定空间中解压、展开并把系统控制权移交给内核
Linux的bootloader
LILOLInux LOader早期的bootloader功能单一已淘汰GRUBGRand Unified BootloaderC5/6 使用GRUB 0.97: GRUB LegacyC7 以后使用GRUB 2.02
GRUB 启动阶段
primary boot loader 1st stageMBR的前446个字节)1.5 stagembr 之后的扇区让stage1中的bootloader能识别stage2所在的分区上的文件 secondary boot loader2nd stage分区文件/boot/grub/
例
[rootCentOS8 ~]#rpm -qa grub*
grub2-tools-minimal-2.02-106.el8.x86_64
grub2-common-2.02-106.el8.noarch
grub2-tools-2.02-106.el8.x86_64
grub2-pc-2.02-106.el8.x86_64
grub2-pc-modules-2.02-106.el8.noarch
grub2-tools-extra-2.02-106.el8.x86_64
grubby-8.40-42.el8.x86_64[rootCentOS8 ~]#rpm -qi grub2-pc
Name : grub2-pc
Epoch : 1
Version : 2.02
Release : 106.el8
Architecture: x86_64
Install Date: Tue 30 May 2023 11:33:23 PM CST
Group : System Environment/Base
Size : 01.3.2.2 CentOS 6 grub 安装
安装grub:
(1)grub-install 安装grub stage1和stage1_5到/dev/DISK磁盘上并复制GRUB相关文件到 DIR/boot
目录下
grub-install --root-directoryDIR /dev/DISK(2) grub
grub root (hd#,#)第#个硬盘第#个分区
grub setup (hd#)例1破坏C6系统的启动文件的第一阶段的446字节然后使用救援模式修复
[rootCentOS6 ~]#hexdump -C -n 512 /dev/sda
00000000 eb 48 90 10 8e d0 bc 00 b0 b8 00 00 8e d8 8e c0 |.H..............|
00000010 fb be 00 7c bf 00 06 b9 00 02 f3 a4 ea 21 06 00 |...|.........!..|
00000020 00 be be 07 38 04 75 0b 83 c6 10 81 fe fe 07 75 |....8.u........u|
00000030 f3 eb 16 b4 02 b0 01 bb 00 7c b2 80 8a 74 03 02 |.........|...t..|
00000040 80 00 00 80 a0 0c 05 00 00 08 fa 90 90 f6 c2 80 |................|
00000050 75 02 b2 80 ea 59 7c 00 00 31 c0 8e d8 8e d0 bc |u....Y|..1......|
00000060 00 20 fb a0 40 7c 3c ff 74 02 88 c2 52 f6 c2 80 |. ..|.t...R...|
00000070 74 54 b4 41 bb aa 55 cd 13 5a 52 72 49 81 fb 55 |tT.A..U..ZRrI..U|
00000080 aa 75 43 a0 41 7c 84 c0 75 05 83 e1 01 74 37 66 |.uC.A|..u....t7f|
00000090 8b 4c 10 be 05 7c c6 44 ff 01 66 8b 1e 44 7c c7 |.L...|.D..f..D|.|
000000a0 04 10 00 c7 44 02 01 00 66 89 5c 08 c7 44 06 00 |....D...f.\..D..|
000000b0 70 66 31 c0 89 44 04 66 89 44 0c b4 42 cd 13 72 |pf1..D.f.D..B..r|
000000c0 05 bb 00 70 eb 7d b4 08 cd 13 73 0a f6 c2 80 0f |...p.}....s.....|
000000d0 84 f0 00 e9 8d 00 be 05 7c c6 44 ff 00 66 31 c0 |........|.D..f1.|
000000e0 88 f0 40 66 89 44 04 31 d2 88 ca c1 e2 02 88 e8 |..f.D.1........|
000000f0 88 f4 40 89 44 08 31 c0 88 d0 c0 e8 02 66 89 04 |...D.1......f..|
00000100 66 a1 44 7c 66 31 d2 66 f7 34 88 54 0a 66 31 d2 |f.D|f1.f.4.T.f1.|
00000110 66 f7 74 04 88 54 0b 89 44 0c 3b 44 08 7d 3c 8a |f.t..T..D.;D.}.|
00000120 54 0d c0 e2 06 8a 4c 0a fe c1 08 d1 8a 6c 0c 5a |T.....L......l.Z|
00000130 8a 74 0b bb 00 70 8e c3 31 db b8 01 02 cd 13 72 |.t...p..1......r|
00000140 2a 8c c3 8e 06 48 7c 60 1e b9 00 01 8e db 31 f6 |*....H|......1.|
00000150 31 ff fc f3 a5 1f 61 ff 26 42 7c be 7f 7d e8 40 |1.....a.B|..}.|
00000160 00 eb 0e be 84 7d e8 38 00 eb 06 be 8e 7d e8 30 |.....}.8.....}.0|
00000170 00 be 93 7d e8 2a 00 eb fe 47 52 55 42 20 00 47 |...}.*...GRUB .G|
00000180 65 6f 6d 00 48 61 72 64 20 44 69 73 6b 00 52 65 |eom.Hard Disk.Re|
00000190 61 64 00 20 45 72 72 6f 72 00 bb 01 00 b4 0e cd |ad. Error.......|
000001a0 10 ac 3c 00 75 f4 c3 00 00 00 00 00 00 00 00 00 |...u...........|
000001b0 00 00 00 00 00 00 00 00 05 7f 0d 00 00 00 80 20 |............... |
000001c0 21 00 83 aa 28 82 00 08 00 00 00 00 20 00 00 aa |!...(....... ...|
000001d0 29 82 83 fe ff ff 00 08 20 00 00 00 80 0c 00 fe |)....... .......|
000001e0 ff ff 83 fe ff ff 00 08 a0 0c 00 80 1a 06 00 fe |................|
000001f0 ff ff 05 fe ff ff 00 88 ba 12 00 78 45 06 55 aa |...........xE.U.|
00000200
[rootCentOS6 ~]#dd if/dev/zero of/dev/sda bs1 count446 #将前446字节写为0
4460 records in
4460 records out
446 bytes (446 B) copied, 0.000366533 s, 1.2 MB/s
[rootCentOS6 ~]#hexdump -C -n 512 /dev/sda -v
00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000070 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000080 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000090 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000000a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000000b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000000c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000000d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000000e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000000f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000100 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000110 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000120 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000130 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000150 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000160 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000170 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000180 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000190 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 80 20 |............... |
000001c0 21 00 83 aa 28 82 00 08 00 00 00 00 20 00 00 aa |!...(....... ...|
000001d0 29 82 83 fe ff ff 00 08 20 00 00 00 80 0c 00 fe |)....... .......|
000001e0 ff ff 83 fe ff ff 00 08 a0 0c 00 80 1a 06 00 fe |................|
000001f0 ff ff 05 fe ff ff 00 88 ba 12 00 78 45 06 55 aa |...........xE.U.|
00000200
[rootCentOS6 ~]#reboot有光盘的情况下 **无光盘的情况下**先尝试网络启动失败后提示没有操作系统 修复
连接光盘重启加载时按下ESC显示boot menu选择光盘启动 选择救援模式 配置语言、键盘、网络等 回车启动一个shell bash-4.1#df #查看我们系统真正的硬盘被挂载到/mnt/sysimage
bash-4.1#chroot /mnt/sysimage/ #切换到系统的硬盘下
bash-4.1#grub-install /dev/sda #修复sda
#提示成功
bash-4.1#sync #将缓冲区内容写入到磁盘防止直接重启而未写入磁盘bash-4.1#hexdump -C -n 512 /dev/sda #查看sda的前512字节内容已经修复
bash-4.1#reboot #重启成功启动 例2破坏C6系统的启动文件的第一阶段的446字节然后使用grub修复
[rootCentOS6 ~]#dd if/dev/zero of/dev/sda bs1 count446 #将前446字节写为0
4460 records in
4460 records out
446 bytes (446 B) copied, 0.000366533 s, 1.2 MB/s[rootCentOS6 ~]#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, TABlists possible command completions. Anywhere else TAB lists the possiblecompletions of a device/filename.]
grub root (hd0,0)
root (hd0,0)Filesystem type is ext2fs, partition type 0x83
grub setup (hd0)
setup (hd0)Checking if /boot/grub/stage1 exists... noChecking if /grub/stage1 exists... yesChecking if /grub/stage2 exists... yesChecking if /grub/e2fs_stage1_5 exists... yesRunning embed /grub/e2fs_stage1_5 (hd0)... 27 sectors are embedded.
succeededRunning install /grub/stage1 (hd0) (hd0)127 p (hd0,0)/grub/stage2 /grub/grub.conf... succeeded
Done.
[rootCentOS6 ~]#hexdump -C -n 512 /dev/sda
00000000 eb 48 90 00 00 00 00 00 00 00 00 00 00 00 00 00 |.H..............|
00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00000030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03 02 |................|
00000040 ff 00 00 20 01 00 00 00 00 02 fa 90 90 f6 c2 80 |... ............|
00000050 75 02 b2 80 ea 59 7c 00 00 31 c0 8e d8 8e d0 bc |u....Y|..1......|
00000060 00 20 fb a0 40 7c 3c ff 74 02 88 c2 52 f6 c2 80 |. ..|.t...R...|
00000070 74 54 b4 41 bb aa 55 cd 13 5a 52 72 49 81 fb 55 |tT.A..U..ZRrI..U|
00000080 aa 75 43 a0 41 7c 84 c0 75 05 83 e1 01 74 37 66 |.uC.A|..u....t7f|
00000090 8b 4c 10 be 05 7c c6 44 ff 01 66 8b 1e 44 7c c7 |.L...|.D..f..D|.|
000000a0 04 10 00 c7 44 02 01 00 66 89 5c 08 c7 44 06 00 |....D...f.\..D..|
000000b0 70 66 31 c0 89 44 04 66 89 44 0c b4 42 cd 13 72 |pf1..D.f.D..B..r|
000000c0 05 bb 00 70 eb 7d b4 08 cd 13 73 0a f6 c2 80 0f |...p.}....s.....|
000000d0 84 f0 00 e9 8d 00 be 05 7c c6 44 ff 00 66 31 c0 |........|.D..f1.|
000000e0 88 f0 40 66 89 44 04 31 d2 88 ca c1 e2 02 88 e8 |..f.D.1........|
000000f0 88 f4 40 89 44 08 31 c0 88 d0 c0 e8 02 66 89 04 |...D.1......f..|
00000100 66 a1 44 7c 66 31 d2 66 f7 34 88 54 0a 66 31 d2 |f.D|f1.f.4.T.f1.|
00000110 66 f7 74 04 88 54 0b 89 44 0c 3b 44 08 7d 3c 8a |f.t..T..D.;D.}.|
00000120 54 0d c0 e2 06 8a 4c 0a fe c1 08 d1 8a 6c 0c 5a |T.....L......l.Z|
00000130 8a 74 0b bb 00 70 8e c3 31 db b8 01 02 cd 13 72 |.t...p..1......r|
00000140 2a 8c c3 8e 06 48 7c 60 1e b9 00 01 8e db 31 f6 |*....H|......1.|
00000150 31 ff fc f3 a5 1f 61 ff 26 42 7c be 7f 7d e8 40 |1.....a.B|..}.|
00000160 00 eb 0e be 84 7d e8 38 00 eb 06 be 8e 7d e8 30 |.....}.8.....}.0|
00000170 00 be 93 7d e8 2a 00 eb fe 47 52 55 42 20 00 47 |...}.*...GRUB .G|
00000180 65 6f 6d 00 48 61 72 64 20 44 69 73 6b 00 52 65 |eom.Hard Disk.Re|
00000190 61 64 00 20 45 72 72 6f 72 00 bb 01 00 b4 0e cd |ad. Error.......|
000001a0 10 ac 3c 00 75 f4 c3 00 00 00 00 00 00 00 00 00 |...u...........|
000001b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 80 20 |............... |
000001c0 21 00 83 aa 28 82 00 08 00 00 00 00 20 00 00 aa |!...(....... ...|
000001d0 29 82 83 fe ff ff 00 08 20 00 00 00 80 0c 00 fe |)....... .......|
000001e0 ff ff 83 fe ff ff 00 08 a0 0c 00 80 1a 06 00 fe |................|
000001f0 ff ff 05 fe ff ff 00 88 ba 12 00 78 45 06 55 aa |...........xE.U.|
00000200例3破坏1.5阶段的第2至第25个扇区将内容置为0然后修复
[rootCentOS6 ~]#dd if/dev/zero of/dev/sda bs512 count25 seek1
250 records in
250 records out
12800 bytes (13 kB) copied, 0.00245147 s, 5.2 MB/s[rootCentOS6 ~]#hexdump -C -n 5120 /dev/sda -v
00000000 eb 48 90 00 00 00 00 00 00 00 00 00 00 00 00 00 |.H..............|
00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03 02 |................|
00000040 ff 00 00 20 01 00 00 00 00 02 fa 90 90 f6 c2 80 |... ............|
00000050 75 02 b2 80 ea 59 7c 00 00 31 c0 8e d8 8e d0 bc |u....Y|..1......|
00000060 00 20 fb a0 40 7c 3c ff 74 02 88 c2 52 f6 c2 80 |. ..|.t...R...|
00000070 74 54 b4 41 bb aa 55 cd 13 5a 52 72 49 81 fb 55 |tT.A..U..ZRrI..U|
00000080 aa 75 43 a0 41 7c 84 c0 75 05 83 e1 01 74 37 66 |.uC.A|..u....t7f|
00000090 8b 4c 10 be 05 7c c6 44 ff 01 66 8b 1e 44 7c c7 |.L...|.D..f..D|.|
000000a0 04 10 00 c7 44 02 01 00 66 89 5c 08 c7 44 06 00 |....D...f.\..D..|
000000b0 70 66 31 c0 89 44 04 66 89 44 0c b4 42 cd 13 72 |pf1..D.f.D..B..r|
000000c0 05 bb 00 70 eb 7d b4 08 cd 13 73 0a f6 c2 80 0f |...p.}....s.....|
000000d0 84 f0 00 e9 8d 00 be 05 7c c6 44 ff 00 66 31 c0 |........|.D..f1.|
000000e0 88 f0 40 66 89 44 04 31 d2 88 ca c1 e2 02 88 e8 |..f.D.1........|
000000f0 88 f4 40 89 44 08 31 c0 88 d0 c0 e8 02 66 89 04 |...D.1......f..|
00000100 66 a1 44 7c 66 31 d2 66 f7 34 88 54 0a 66 31 d2 |f.D|f1.f.4.T.f1.|
00000110 66 f7 74 04 88 54 0b 89 44 0c 3b 44 08 7d 3c 8a |f.t..T..D.;D.}.|
00000120 54 0d c0 e2 06 8a 4c 0a fe c1 08 d1 8a 6c 0c 5a |T.....L......l.Z|
00000130 8a 74 0b bb 00 70 8e c3 31 db b8 01 02 cd 13 72 |.t...p..1......r|
00000140 2a 8c c3 8e 06 48 7c 60 1e b9 00 01 8e db 31 f6 |*....H|......1.|
00000150 31 ff fc f3 a5 1f 61 ff 26 42 7c be 7f 7d e8 40 |1.....a.B|..}.|
00000160 00 eb 0e be 84 7d e8 38 00 eb 06 be 8e 7d e8 30 |.....}.8.....}.0|
00000170 00 be 93 7d e8 2a 00 eb fe 47 52 55 42 20 00 47 |...}.*...GRUB .G|
00000180 65 6f 6d 00 48 61 72 64 20 44 69 73 6b 00 52 65 |eom.Hard Disk.Re|
00000190 61 64 00 20 45 72 72 6f 72 00 bb 01 00 b4 0e cd |ad. Error.......|
000001a0 10 ac 3c 00 75 f4 c3 00 00 00 00 00 00 00 00 00 |...u...........|
000001b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 80 20 |............... |
000001c0 21 00 83 aa 28 82 00 08 00 00 00 00 20 00 00 aa |!...(....... ...|
000001d0 29 82 83 fe ff ff 00 08 20 00 00 00 80 0c 00 fe |)....... .......|
000001e0 ff ff 83 fe ff ff 00 08 a0 0c 00 80 1a 06 00 fe |................|
000001f0 ff ff 05 fe ff ff 00 88 ba 12 00 78 45 06 55 aa |...........xE.U.|
00000200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000210 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000220 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000230 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000240 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000250 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000260 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000270 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000280 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000290 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000002a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000002b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000002c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000002d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000002e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000002f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000300 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000310 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000320 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000330 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000340 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000350 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000360 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000370 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000380 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000390 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000003a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000003b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000003c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000003d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000003e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000003f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000400 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000410 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000420 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000430 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000440 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000450 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000460 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000470 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000480 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000490 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000004a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000004b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000004c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000004d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000004e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000004f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000500 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000510 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000520 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000530 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000540 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000550 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000560 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000570 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000580 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000590 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000005a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000005b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000005c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000005d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000005e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000005f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000600 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000610 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000620 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000630 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000640 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000650 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000660 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000670 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000680 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000690 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000006a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000006b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000006c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000006d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
[rootCentOS6 ~]#reboot重启后系统无法打开但错误提示不同 此时1阶段正常系统认为硬盘可以启动所以一直在加载而不去寻找光盘等设备来启动就会卡在这里
**修复**同样的进入救援模式然后切换根然后grub-install /dev/sda即可 1.3.2.3 grub legacy 管理
配置文件 /boot/grub/grub.conf -- /etc/grub.confstage2及内核等通常放置于一个基本磁盘分区
grub legacy 功用
提供启动菜单、并提供交互式接口 a内核参数e编辑模式用于编辑菜单c命令模式交互式接口 加载用户选择的内核或操作系统 允许传递参数给内核可隐藏启动菜单 为菜单提供了保护机制 为编辑启动菜单进行认证为启用内核或操作系统进行认证
grub的命令行接口
help 获取帮助列表
help KEYWORD 详细帮助信息
find (hd#,#)/PATH/TO/SOMEFILE:
root (hd#,#)
kernel /PATH/TO/KERNEL_FILE 设定本次启动的内核文件额外还可添加许多内核支持使用的cmdline参数
例如 max_loop100 selinux0 init/path/to/initinitrd /PATH/TO/INITRAMFS_FILE 设定为选定的内核提供额外文件的ramdisk
boot 引导启动选定的内核cat /proc/cmdline 内核参数
内核参数文档
/usr/share/doc/kernel-doc-2.6.32/Documentation/kernel-parameters.txtgrub legacy识别硬盘设备
(hd#,#)
hd# 磁盘编号用数字表示;从0开始编号
# 分区编号用数字表示从0开始编号示例
(hd0,0) 第一块硬盘第一个分区手动在grub命令行接口启动系统
grub root (hd#,#)
grub kernel /vmlinuz-VERSION-RELEASE ro root/dev/DEVICE
grub initrd /initramfs-VERSION-RELEASE.img
grub bootgrub legacy配置文件 /boot/grub/grub.conf
default# 设定默认启动的菜单项;落单项(title)编号从0开始
timeout# 指定菜单项等待选项选择的时长
splashimage(hd#,#)/PATH/XPM_FILE 菜单背景图片文件路径
password [--md5 | encrypt] STRING 启动菜单编辑认证
hiddenmenu 隐藏菜单
title TITLE 定义菜单项“标题”可出现多次
root (hd#,#) 查找stage2及kernel文件所在设备分区;为grub的根
kernel /PATH/TO/VMLINUZ_FILE [PARAMETERS] 启动的内核
initrd /PATH/TO/INITRAMFS_FILE 内核匹配的ramfs文件
password [--md5|--encrypted ] STRING 启动选定的内核或操作系统时进行认证grub加密生成grub口令
grub-md5-crypt
grub-crypt破解root口令
(1)编辑grub菜单(选定要编辑的title而后使用a 或 e 命令)
(2)在选定的kernel后附加1sSsingle 都可以进入单用户模式
(3)在kernel所在行键入“b”命令范例 给grub 添加密码防止破解root密码
[rootcentos6 ~]#grub-crypt
Password:
Retype password:
S6SRedtvBe0DOsM8yKqSykwmmnHsDb9WDRUuZbC3H1ZNwITf/Mh88MXa3JzXToxyyohXIXFWLIOMdgmYFfkwxxkP.VW3ypITa4P5zUKuT.[rootcentos6 ~]#vim /boot/grub/grub.conf
default0
timeout5
password --encrypt #加上这一行
56SRedtvBe0DOsM8ykqSykwmmnHSDb9WDRUuZbC3H1ZNwI1f/Mh88MXa3JzX1oxyyohXIXFWLIOMdgmYFfkwxxkP.VW3ypI1a4P5zUKuT.
splashimage(hd0,0)/grub /splash.xpm.gz
hiddenmenu
title Centos 6 (2.6.32-754.e16.x86_64)#然后在系统选择时输入口令才能进入编辑
#不过进入救援模式仍然可以跳过这些安全步骤并修改密码1.3.3 加载 kernel
kernel自身初始化过程
探测可识别到的所有硬件设备加载硬件动程序 (借助于ramdisk加载动)以只读方式挂载根文件系统运行用户空间的第一个应用程序/sbin/init
Linux内核特点
支持模块化.ko (内核对象)如 文件系统硬件驱动网络协议等支持内核模块的动态装载和卸载
内核组成部分 核心文件 /boot/vmlinuz-VERSION-release ramdisk辅助的伪根系统加载相应的硬件驱动ramdisk -- ramfs 提高速度 C 5 /boot/initrd-VERSION-release.img C 6以后版本 /boot/initramfs-VERSION-release.img 模块文件 /ib/modules/VERSION-release
ramdisk文件的制作
mkinitrd命令
mkinitrd /boot/initramfs-$(uname -r).img $(uname -r)dracut命令
dracut /boot/initramfs-$(uname -r).img $(uname -r)例误删除/boot/initramfs-2.6.32-754.el6.x86_64.img文件导致系统无法启动修复
[rootCentOS6 boot]#rm -f initrd-2.6.32-754.el6.x86_64kdump.img
[rootCentOS6 boot]#reboot
#进入救援模式
#chroot /mnt/sysimage #切根
#mkinitrd /boot/initramfs-uname -r.img uname -r
#sync
#reboot例误删除/boot/vmlinuz-2.6.32-754.el6.x86_64文件即内核文件导致系统无法启动修复
[rootCentOS6 boot]#rm -f /boot/vmlinuz-2.6.32-754.el6.x86_64
#方式1
[rootCentOS6 boot]#reboot
#进入救援模式
#chroot /mnt/sysimage #切根
#mount /dev/sr0 /mnt/ #挂载光盘
#cp /mnt/isolinux/vmlinuz /boot/vmlinuz-2.6.32-754.el6.x86_64
#sync
#reboot#方式2
#由于vmlinuz文件来源于光盘里的kernel包直接重装即可
[rootCentOS6 boot]#rpm -qf vmlinuz-2.6.32-754.el6.x86_64
kernel-2.6.32-754.el6.x86_64例误删除/boot/*grub和内核都被删除进行故障恢复
#先修复内核再修复Grub范例生成背景图片
[rootcentos6 ~]#convert -resize 640x480 -colors 14 winner.png splash.xpm
[rootcentos6 ~]#more splash.xpm
#生成splash.xpm.gz
[rootacentos6 ~]#qzip splash.xpm
[rootcentos6 ~]#mv splash.xpm.gz /boot/grub1.3.4 init 初始化
使POST -- BootSeguence (BIOS) --Bootloader(MBR) -- kernel(ramdisk) -- rootfs(只读) --init(systemd)
init程序的类型 SysV initC5之前 配置文件/etc/inittab Upstart initC 6 配置文件/etc/inittab/etc/init/*.conf SystemdsystemdC 7 配置文件 /usr/lib/systemd/system/etc/systemd/system
1.3.4.1 运行级别
运行级别 为系统运行或维护等目的而设定0-67个级别一般使用35做为默认级别
0关机
1单用户模式(root自动登录)single维护模式
2多用户模式启动网络功能但不会启动NFS 维护模式
3多用户模式正常模式文本界面
4预留级可同3级别
5多用户模式正常模式图形界面
6重启切换级别
init #查看级别
runlevel
who -r定义运行级别
/etc/inittabC 5的inittab文件还定义以下内容
初始运行级别(RUN LEVEL)
系统初始化脚本
对应运行级别的脚本目录
捕获某个关键字顺序
定义UPS电源终端/恢复脚本
在虚拟控制台生成getty
在运行级别5初始化XC 5的inittab文件每一行格式
id:runlevel:action:processid是惟一标识该项的字符序列
runlevels 定义了操作所使用的运行级别
action指定了要执行的特定操作wait 切换至此级别运行一次respawn 此process终止就重新启动之initdefault设定默认运行级别;process省略sysinit设定系统初始化方式
process定义了要执行的进程例CentOS 6 /etc/inittab和相关文件
C6 init程序为 upstart 其配置文件/etc/inittab/etc/init/*.conf配置文件的语法 遵循 upstart配置文件语法格式和C 5不同
[rootCentOS6 ~]#cat /etc/inittab
# inittab is only used by upstart for the default runlevel.
#
# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# System initialization is started by /etc/init/rcS.conf
#
# Individual runlevels are started by /etc/init/rc.conf
#
# Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
#
# Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf,
# with configuration in /etc/sysconfig/init.
#
# For information on how to write upstart event handlers, or how
# upstart works, see init(5), init(8), and initctl(8).
#
# Default runlevel. The runlevels used are:
# 0 - halt (Do NOT set initdefault to this)
# 1 - Single user mode
# 2 - Multiuser, without NFS (The same as 3, if you do not have networking)
# 3 - Full multiuser mode
# 4 - unused
# 5 - X11
# 6 - reboot (Do NOT set initdefault to this)
#
id:3:initdefault:例control -alt-delete键默认行为是重启工作中可以将其注释以防止误触
[rootCentOS6 init]#cat /etc/init/control-alt-delete.conf
# control-alt-delete - emergency keypress handling
#
# This task is run whenever the Control-Alt-Delete key combination is
# pressed. Usually used to shut down the machine.
#
# Do not edit this file directly. If you want to change the behaviour,
# please create a file control-alt-delete.override and put your changes there.start on control-alt-deleteexec /sbin/shutdown -r now Control-Alt-Delete pressed例ntsysv图形界面修改服务空格开启或关闭 例一次性修改atd的7种模式
[rootCentOS6 init]#chkconfig --list atd
atd 0:off 1:off 2:off 3:on 4:on 5:on 6:off
[rootCentOS6 init]#chkconfig --level 34 atd off
[rootCentOS6 init]#chkconfig --list atd
atd 0:off 1:off 2:off 3:off 4:off 5:on 6:off
[rootCentOS6 init]#chkconfig atd on
[rootCentOS6 init]#chkconfig --list atd
atd 0:off 1:off 2:on 3:on 4:on 5:on 6:off例设置服务开机不启动
[rootCentOS6 init]#service iptables stop #关闭服务
[rootCentOS6 init]#chkconfig iptables off #设置开机不启动开机启动则on1.3.4.2 初始化脚本 sysinit
在所有服务加载之前执行初始化的脚本
/etc/rc.d/rc.sysinit#由 rcS.conf文件调用
[rootCentOS6 init]#cat /etc/init/rcS.conf
exec /etc/rc.d/rc.sysinit系统初始化脚本功能
设置主机名设置欢迎信息激活udev和selinux挂载/etc/fstab文件中定义的文件系统检测根文件系统并以读写方式重新挂载根文件系统设置系统时钟激活swap设备根据/etc/sysctl.conf文件设置内核参数激活lvm及software raid设备加载额外设备的驱动程序清理操作
1.3.4.3 服务管理
service 命令:手动管理服务
service 服务 start|stop|restart
service --status-all由rc.conf文件调用rc.drc调用服务脚本
[rootCentOS6 init]#cat /etc/init/rc.conf
exec /etc/rc.d/rc $RUNLEVEL/etc/rc.d/rc 控制服务脚本的开机自动运行
for srv in /etc/rc.d/rcN.d/k*; do$srv stop
donefor srv in /etc/rc.d/rcN.d/s*; do$srv start
done说明: rc N -- 意味着读取/etc/rc.d/rcN.d/
K: K##: ##运行次序数字越小越先运行数字越小的服务通常为依赖到别的服务s: S##: ##运行次序数字越小越先运行数字越小的服务通常为被依赖到的服务
配置服务开机启动
chkconfig命令ntsysv命令
chkconfig 命令管理服务
#查看服务在所有级别的启动或关闭设定情形:
chkconfig [--list] [name]#添加服务
Sysv的服务脚本放置于/etc/rc.d/init.d (/etc/init.d)
#!/bin/bash
chkconfig: LLLL nn nn #LLLL 表示初始在哪个级别下启动-表示都不启动
description :描述信息chkconfig --add name#删除服务
chkconfig --del name#修改指定的运行级别
chkconfig [--level levels] name onlofflreset
说明: --level LLLL: 指定要设置的级别;省略时表示23451.3.4.4 非独立服务
服务分为独立服务和非独立服务
瞬态 (Transient) 服务被超级守护进程 xinetd 进程所管理也称为非独立服务即用户不访问/使用该服务时服务关闭被xinetd进程所监控当有用户访问某非独立服务时则唤醒该非独立服务使用结束则关闭服务
进入的请求首先被xinetd代理
配置文件:
etc/xinetd.conf
/etc/xinetd.d/service用chkconfig控制非独立服务开机启动
示例: chkconfig tftp on1.3.4.5 开机启动文件 rc.local
/etc/rc.d/rc.local注意: 正常级别下最后启动一个服务S99local没有链接至/etc/rc.d/init.d一个服务脚本而是指向了/etc/rc.d/rc.local脚本
不便或不需写为服务脚本放置于/etc/rc.d/init.d/目录且又想开机时自动运行的命令可直接放警于/etc/rc.d/rc.local文件中 /etc/rc.d/rc.local在指定运行级别脚本后运行
1.3.5 Centos 启动过程总结
/sbin/init -- (/etc/inittab) -- 设置默认运行级别 -- 运行系统初始脚本/etc/rc.d/rc.sysinit、完成系统初始化 --(关闭对应下需要关闭的服务)启动需要启动服务/etc/rc#.d/Sxxx/etc/rc.d/rc.local -- 设置登录终端
参看: http://s4.51cto.com/wyfs02/M02/87/20/wKiom1fVBELjXsvaAAUkuL83t2Q304.jpg 1.4 自制linux系统
1.4.0为当前Linux系统增加硬盘
在现有Linux系统上构建系统所以先在其上面加一块硬盘上面存放文件系统与数据
在VMware上增加硬盘 默认当前无法找到硬盘 使用命令扫描一下磁盘
[rootCentOS6 ~]#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 1G 0 part /boot
├─sda2 8:2 0 100G 0 part /
├─sda3 8:3 0 48.8G 0 part /data
├─sda4 8:4 0 1K 0 part
└─sda5 8:5 0 4G 0 part [SWAP]
[rootCentOS6 ~]#echo - - - /sys/class/scsi_host/host0/scan
[rootCentOS6 ~]#echo - - - /sys/class/scsi_host/host1/scan
[rootCentOS6 ~]#echo - - - /sys/class/scsi_host/host2/scan
[rootCentOS6 ~]#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 1G 0 part /boot
├─sda2 8:2 0 100G 0 part /
├─sda3 8:3 0 48.8G 0 part /data
├─sda4 8:4 0 1K 0 part
└─sda5 8:5 0 4G 0 part [SWAP]
sdb 8:16 0 20G 0 disk1.4.1 分区并创建文件系统
fdisk /dev/sdb#分两个必要的分区
[rootcentos6 ~]#echo -e n\np\n1\n\n1G\nw\n fdisk /dev/sdb #\n表示回车给第一个分区分1G空间
[rootcentos6 ~]#echo -e n\np\n2\n\n\n\nw\n fdisk /dev/sdb #将剩下空间给第二个分区
/dev/sdb1对应/boot /dev/sdb2对应根/[rootcentos6 ~]#mkfs.ext4 /dev/sdb1
[rootcentos6 ~]#mkfs.ext4 /dev/sdb2例
#1手动添加
[rootCentOS6 ~]#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 0x85b35a65.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content wont be recoverable.Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)WARNING: DOS-compatible mode is deprecated. Its strongly recommended toswitch off the mode (command c) and change display units tosectors (command u).Command (m for help):
Command (m for help): n
Command actione extendedp 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): 1GCommand (m for help): w
The partition table has been altered!Calling ioctl() to re-read partition table.
Syncing disks.
#2非交互式直接添加
[rootCentOS6 ~]#echo -e n\np\n2\n\n\n\nw\n | fdisk /dev/sdbWARNING: DOS-compatible mode is deprecated. Its strongly recommended toswitch off the mode (command c) and change display units tosectors (command u).Command (m for help): Command actione extendedp primary partition (1-4)
Partition number (1-4): First cylinder (133-2610, default 133): Using default value 133
Last cylinder, cylinders or size{K,M,G} (133-2610, default 2610): Using default value 2610Command (m for help): Command (m for help): The partition table has been altered!Calling ioctl() to re-read partition table.
Syncing disks.
[rootCentOS6 ~]#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 1G 0 part /boot
├─sda2 8:2 0 100G 0 part /
├─sda3 8:3 0 48.8G 0 part /data
├─sda4 8:4 0 1K 0 part
└─sda5 8:5 0 4G 0 part [SWAP]
sdb 8:16 0 20G 0 disk
├─sdb1 8:17 0 1G 0 part
└─sdb2 8:18 0 19G 0 part#格式化
[rootCentOS6 ~]#mkfs.ext4 /dev/sdb1
mke2fs 1.41.12 (17-May-2010)
Filesystem label
OS type: Linux
Block size4096 (log2)
Fragment size4096 (log2)
Stride0 blocks, Stripe width0 blocks
66384 inodes, 265064 blocks
13253 blocks (5.00%) reserved for the super user
First data block0
Maximum filesystem blocks272629760
9 block groups
32768 blocks per group, 32768 fragments per group
7376 inodes per group
Superblock backups stored on blocks:32768, 98304, 163840, 229376Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: doneThis filesystem will be automatically checked every 34 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[rootCentOS6 ~]#mkfs.ext4 /dev/sdb2
mke2fs 1.41.12 (17-May-2010)
Filesystem label
OS type: Linux
Block size4096 (log2)
Fragment size4096 (log2)
Stride0 blocks, Stripe width0 blocks
1245184 inodes, 4976133 blocks
248806 blocks (5.00%) reserved for the super user
First data block0
Maximum filesystem blocks4294967296
152 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,4096000Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: doneThis filesystem will be automatically checked every 22 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.1.4.2 挂载boot
[rootcentos6 ~]#mkdir /mnt/boot #子目录必须为boot
[rootcentos6 ~]#mount /dev/sdb1 /mnt/boot/1.4.3 安装grub
[rootcentos6 ~]#grub-install --root-directory/mnt /dev/sdb例
[rootCentOS6 ~]#mkdir /mnt/boot
[rootCentOS6 ~]#mount /dev/sdb1 /mnt/boot/
[rootCentOS6 ~]#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
[rootCentOS6 ~]#ls /mnt/boot
grub lostfound
[rootCentOS6 ~]#ls /mnt/boot/grub
device.map fat_stage1_5 iso9660_stage1_5 minix_stage1_5 stage1 ufs2_stage1_5 xfs_stage1_5
e2fs_stage1_5 ffs_stage1_5 jfs_stage1_5 reiserfs_stage1_5 stage2 vstafs_stage1_51.4.4 准备内核和initramfs文件
[rootCentOS6 ~]#cp /boot/vmlinuz-2.6.32-754.el6.x86_64 /mnt/boot/vmlinuz
[rootCentOS6 ~]#cp /boot/initramfs-2.6.32-754.el6.x86_64.img /mnt/boot/initramfs1.4.5 手动建立grub.conf
[rootCentOS6 ~]#cat /mnt/boot/grub/grub.conf
default0
timeout5
title joyce linux
root (hd0,0)
kernel /vmlinuz root/dev/sda2 selinux0 init/bin/bash
initrd /initramfs[rootCentOS6 ~]#tree /mnt/boot
/mnt/boot
├── grub
│ ├── device.map
│ ├── e2fs_stage1_5
│ ├── fat_stage1_5
│ ├── ffs_stage1_5
│ ├── grub.conf
│ ├── iso9660_stage1_5
│ ├── jfs_stage1_5
│ ├── minix_stage1_5
│ ├── reiserfs_stage1_5
│ ├── stage1
│ ├── stage2
│ ├── ufs2_stage1_5
│ ├── vstafs_stage1_5
│ └── xfs_stage1_5
├── initramfs
├── lostfound
└── vmlinuz1.4.6 准备根下面相关程序和库
mkdir /mnt/sysroot
mount /dev/sdb2 /mnt/sysroot
mkdir -pv /mnt/sysroot/{etc,lib,lib64,bin,sbin,tmp,var,usr,sys,proc,opt,home,root,boot,dev,mnt,media}
复制bash等命令和相关库文件如: bash,ifconfig,insmod,ping,mount,ls,cat,df,lsblk,blkid,fdisk,tree,ip,ps等#查询网卡驱动并拷贝
[rootCentOS6 ~]#ethtool -i eth0
driver: e1000
version: 7.3.21-k8-NAPI
firmware-version:
bus-info: 0000:02:01.0
supports-stalistics: yes
supports-test: yes
supports-eeprom-access: yes
supports-register-dump: yes
supports-priv-flags: no
[rootCentOS6 ~]#modinfo -n e1000
/lib/modules/2.6.32-754.el6.x86_64/kernel/drivers/net/e1000/e1000.ko
[rootCentOS6 ~]#cp /lib/modules/2.6.32-754.el6.x86_64/kernel/drivers/net/e1000/e1000.ko /mnt/sysroot/lib/ #将网卡驱动放在/mnt/sysroot/lib下[rootcentos6 ~]#chroot /mnt/sysroot1.4.7 准备新的虚拟机
将当前C6机器关机将刚创建的硬盘拷贝到test文件夹中 创建一个新的Linux6虚拟机将前一虚拟机sdb硬盘对应的vmdk文件增加进去删除原有磁盘 开机 1.5 启动过程的故障排错
1.5.1 实战案例
故障删除 /sbin/init 无法启动
恢复过程
先进入grub菜单在kernel参数后加 selinux0 init/bin/bash
mount -o remount,rw /
mount /dev/sr0 /mnt/
rpm2cpio /mnt/Packages/upstart.xxx.rpm cpio -idv ./sbin/init
mv ./sbin/init /sbin/1.5.2 实战案例
故障rm -rf /boot/* 和 /etc/fstab 进行恢复
恢复过程
1.用光盘进入 rescue mode找到/ 所在分区并恢复/etc/fstab
进入救援模式由于没有分区表因此无法挂载操作系统的根 fdisk -l
mkdir /mnt/rootdir
mount /dev/sdaN /mnt/rootdir
ls /mnt/rootdir
mount /dev/sda2 /mnt/rootdirvim /mnt/rootdir/etc/fstab
/dev/sda1 /boot ext4 defaults 0 0
/dev/sda2 / ext4 defaults 0 0
/dev/sda3 /data ext4 defaults 0 0
/dev/sda5 swap swap defaults 0 0
reboot2.rescue mode 恢复内核和initrd 文件
/dev/sda2 -- /mnt/sysimagechroot /mnt/sysimage
mount /dev/srO /mnt/
#方法1
rpm -ivh /mnt/Packages/kernel.xxxx.rpm --force#方法2
cp /mnt/isolinux/vmlinuz /boot/
mkinitrd /boot/initramfs.img uname -r3.修复grub
grub-install /dev/sda
vim /boot/grub/grub.conf 方法2
[rootcentos6 ~]#cat /boot/grub/grub.conf
default0
timeout5
title centos
kernel /vmlinuz root/dev/sda2
initrd /initramfs.img4.reboot
2 /proc 目录和内核参数管理
/proc目录: 内核把自己内部状态信息及统计信息以及可配置参数通过proc伪文件系统加以输出帮助: man proc 内核参数
只读:只用于输出信息可写: 可接受用户指定“新值”来实现对内核某功能或特性的配置
/proc/sys 设置
sysctl命令用于查看或设定此目录中诸多参数
sysctl -w path.to.parameterVALUE例
[rootCentOS6 ~]#cat /proc/sys/net/ipv4/ip_forward
0
[rootCentOS6 ~]#echo 1 /proc/sys/net/ipv4/ip_forward
#等价于
[rootCentOS6 ~]#sysctl -w net.ipv4.ip_forward1不过这是临时修改无法持久保存
默认配置文件/etc/sysct.conf 总文件及以下文件
/run/sysctl.d/*.conf
/etc/sysctl.d/*.conf
/usr/local/lib/sysctl.d/* .conf
/usr/lib/sysctl.d/*.conf
lib/sysctl.d/* .conf
etc/sysctl.conf最好是分类单独放一个或者放总文件里
范例:修改主机名
sysctl -w kernel.hostnamemail.joyce.comecho命令通过重定向方式也可以修改大多数参数的值
echo VALUE” /proc/sys/path/to/parameter范例:
echo “websrv” /proc/sys/kernel/hostnamesysctl命令 临时设置某参数 sysctl -w parameterVALUE通过读取配置文件设置参数 sysctl -p [/path/to/conf_filel查看所有生效参数 sysctl -a常用的内核参数
net.ipv4.ip_forward
net.ipv4.icmp_echo_ignore_all #设置1则其他主机无法ping通本主机
net.ipv4.ip_nonocal_bind #允许应用程序可以监听本地不存在的IP
vm.drop_caches #可以释放缓冲区
fs.file-max 1020000 #最多可以打开的文件数打开一个文件分配一个文件描述符例
[rootcentos8 ~]#cat /proc/sys/net/ipv4/icmp_echo_ignore_all
0
[rootcentos8 ~]#vim /etc/sysctl.d/test.conf
[rootcentos8 ~]#cat /etc/sysctl.d/test.conf
net.ipv4.icmp_echo_ignore_all1
[rootcentos8 ~]#sysctl -p /etc/sysctl.d/test.conf
net.ipv4.icmp_echo_ignore_all 1
[rootcentos8 ~]#cat /proc/sys/net/ipv4/icmp_echo_ignore_all
13 /sys 目录
/sys目录: 使用sysfs文件系统为用户使用的伪文件系统输出内核识别出的各硬件设备的相关属性信息也有内核对硬件特性的设定信息有些参数是可以修改的用于调整硬件工作特性
udev通过此路径下输出的信息动态为各设备创建所需要设备文件udev是运行用户空间程序专用工具: udevadminhotplug
udev为设备创建设备文件时会读取其事先定义好的规则文件一般在/etc/udev/rules.d及/usr/lib/udev/rules.d目录下
4 内核模块管理和编译
单内核体系设计、但充分借鉴了微内核设计体系的优点为内核引入模块化机制
内核组成部分:、
kernel: 内核核心一般为bzlmage通常在/boot目录下名称为 vmlinuz-VERSION-RELEASEkernel object: 内核对象一般放置于/lib/modules/VERSION-RELEASE/辅助文件: ramdisk、initrdC5及以前模拟磁盘进入后还要进入文件系统、initramfsC6及以后模拟文件系统直接接触文件
4.1 内核版本
运行中的内核
uname命令
uname - print system informationuname [OPTION]..
选项
-n: 显示节点名称
-r: 显示VERSION-RELEASE
-a: 显示所有信息4.2 内核模块命令
lsmod命令
显示由核心已经装载(已被使用的)的内核模块显示的内容来自于: /proc/modules文件
modinfo命令
功能:管理内核模块
配置文件: /etc/modprobe.conf,/etc/modprobe.d/*.conf显示模块的详细描述信息
modinfo [ -k kernel ] [ modulename | filename... ]常用选项:
-n:只显示模块文件路径-
-p:显示模块参数
-a:作者
-d:描述装载或卸载内核模块
modprobe [ -C config-file ] [ modulename ] [ module parame-ters... ]
modprobe [ -r ] modulename...depmod命令: 内核模块依赖关系文件及系统信息映射文件的生成工具
insmod命令: 指定模块文件不能自动解决依赖模块
insmod [ filename ] [ module options...]范例:
insmod modinfo -n exportfs
Insmod modinfo -n xfsrmmod命令:卸载模块类似于modprobe -r
rmmod [ modulename ]范例:
rmmod xfs
rmmod exportfs4.3 编译内核
编译安装内核准备
准备好开发环境获取目标主机上硬件设备的相关信息获取目标主机系统功能的相关信息例如:需要启用相应的文件系统获取内核源代码包www.kernel.org
4.3.1 编译准备
4.3.1.1.目标主机硬件设备相关信息
CPU:
cat /proc/cpuinfo
x86info -a
lscpulsblk 块设备 全部硬件设备信息: hal-device: Centos 6
4.3.1.2 开发环境相关包
安装相对应包gcc make ncurses-devel flex bison openssl-devel elfutils-libelf-devel
4.3.1.3 内核编译安装实现 下载源码文件 准备文本配置文件/boot/config-uname-r make menuconfig: 配置内核选项相当于./configure [ ] : N #未启用
[M] : M #存放在lib下的独立模块
[*] : Y #存放在核心里make [-j #] 或者用以下两步实现 make -j # bzlmage #编译内核文件vmlinuz
make -i # modules #编译lib/modules下的文件安装模块: make modules_install 安装内核相关文件: make install 安装bzlmage为 /boot/vmlinuz-VERSION-RELEASE 生成initramfs文件 编辑grub的配置文件
4.3.1.4 编译安装内核实战案例
简述
[rootCentOS8 ~]#yum -y install gcc make ncurses-devel flex bison openssl-devel elfutils-libelf-devel
[rootcentos8 ~]#tar xf linux-5.4.13.tar.xz -C /usr/src
[rootcentos8 ~]#cd /usr/src
[rootcentos8 ~]#In -sv Tinux-5.4.13 Tinux
[rootacentos8 ~]#cd /usr/src/Tinux
[rootcentos8 ~]#cp /boot/config-$(uname -r) ./.config
[rootcentos8 ~]#vim .config
# CONFIG MODULE SIG is not set
CONFIG_SYSTEM_TRUSTED KEYS
# CONFIG DEBUG INFO is not set
[rootacentos8 ~]#make hep
[rootacentos8 ~]#make menuconfig
[rootacentos8 ~]#make -j 2或者 make -j 2 bzImage ; make -j 2 modules
[rootacentos8 ~]#make modules install
[rootcentos8 ~]#make install
[rootcentos8 ~]#reboot例为C8安装最新内核6.4.11
[rootCentOS8 ~]#yum -y install gcc make ncurses-devel flex bison openssl-devel elfutils-libelf-devel
Last metadata expiration check: 1:31:08 ago on Sun 20 Aug 2023 10:37:38 PM CST.
Package gcc-8.5.0-4.el8_5.x86_64 is already installed.
Package make-1:4.2.1-10.el8.x86_64 is already installed.
Package ncurses-devel-6.1-9.20180224.el8.x86_64 is already installed.
Package openssl-devel-1:1.1.1k-5.el8_5.x86_64 is already installed.
Dependencies resolved.
Package Architecture Version Repository SizeInstalling:bison x86_64 3.0.4-10.el8 AppStream 688 kelfutils-libelf-devel x86_64 0.185-1.el8 BaseOS 59 kflex x86_64 2.6.1-9.el8 AppStream 320 kTransaction SummaryInstall 3 PackagesTotal download size: 1.0 M
Installed size: 3.0 M
Downloading Packages:
(1/3): elfutils-libelf-devel-0.185-1.el8.x86_64.rpm 131 kB/s | 59 kB 00:00
(2/3): flex-2.6.1-9.el8.x86_64.rpm 339 kB/s | 320 kB 00:00
(3/3): bison-3.0.4-10.el8.x86_64.rpm 569 kB/s | 688 kB 00:01
---------------------------------------------------------------------------------------------------
Total 878 kB/s | 1.0 MB 00:01
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transactionPreparing : 1/1Installing : elfutils-libelf-devel-0.185-1.el8.x86_64 1/3Installing : flex-2.6.1-9.el8.x86_64 2/3Running scriptlet: flex-2.6.1-9.el8.x86_64 2/3Installing : bison-3.0.4-10.el8.x86_64 3/3Running scriptlet: bison-3.0.4-10.el8.x86_64 3/3Verifying : bison-3.0.4-10.el8.x86_64 1/3Verifying : flex-2.6.1-9.el8.x86_64 2/3Verifying : elfutils-libelf-devel-0.185-1.el8.x86_64 3/3Installed:bison-3.0.4-10.el8.x86_64 elfutils-libelf-devel-0.185-1.el8.x86_64 flex-2.6.1-9.el8.x86_64Complete![rootCentOS8 ~]#tar xvf linux-6.4.11.tar.xz -C /usr/local/src
[rootCentOS8 ~]#cd /usr/local/src
[rootCentOS8 src]#ls
httpd-2.4.57 httpd-2.4.57.tar.bz2 linux-6.4.11
[rootCentOS8 src]#du -sh . #查看目录总大小
1.5G
[rootCentOS8 src]#find -name *.c | wc -l #.c后缀文件个数
32793
[rootCentOS8 src]#find -name *.c | xargs cat|wc -l #所有.c文件总行数
23223391
[rootCentOS8 src]#cd linux-6.4.11/
[rootCentOS8 linux-6.4.11]#ls
arch CREDITS fs ipc lib mm samples tools
block crypto include Kbuild LICENSES net scripts usr
certs Documentation init Kconfig MAINTAINERS README security virt
COPYING drivers io_uring kernel Makefile rust sound
[rootCentOS8 linux-6.4.11]#cp /boot/config-4.18.0-348.el8.x86_64 .config
[rootCentOS8 linux-6.4.11]#ls -a
. .config .get_maintainer.ignore Kbuild Makefile scripts
.. COPYING .gitattributes Kconfig mm security
arch CREDITS .gitignore kernel net sound
block crypto include lib README tools
certs Documentation init LICENSES rust usr
.clang-format drivers io_uring .mailmap .rustfmt.toml virt
.cocciconfig fs ipc MAINTAINERS samples[rootCentOS8 linux-6.4.11]#vim .config
# CONFIG_MODULE_SIG is not set #将其注释
CONFIG_SYSTEM_TRUSTED KEYS #删除中间内容
# CONFIG DEBUG INFO is not set[rootCentOS8 linux-6.4.11]#make hel p
[rootCentOS8 linux-6.4.11]#make menuconfigHOSTCC scripts/basic/fixdepHOSTCC scripts/kconfig/mconf.oHOSTCC scripts/kconfig/lxdialog/checklist.oHOSTCC scripts/kconfig/lxdialog/inputbox.oHOSTCC scripts/kconfig/lxdialog/menubox.oHOSTCC scripts/kconfig/lxdialog/textbox.oHOSTCC scripts/kconfig/lxdialog/util.oHOSTCC scripts/kconfig/lxdialog/yesno.oHOSTCC scripts/kconfig/confdata.oHOSTCC scripts/kconfig/expr.oLEX scripts/kconfig/lexer.lex.cYACC scripts/kconfig/parser.tab.[ch]HOSTCC scripts/kconfig/lexer.lex.oHOSTCC scripts/kconfig/menu.oHOSTCC scripts/kconfig/parser.tab.oHOSTCC scripts/kconfig/preprocess.oHOSTCC scripts/kconfig/symbol.oHOSTCC scripts/kconfig/util.oHOSTLD scripts/kconfig/mconf
.config:569:warning: symbol value m invalid for I8K
.config:3027:warning: symbol value m invalid for ISDN_CAPI
.config:6142:warning: symbol value m invalid for VFIO_VIRQFD
configuration written to .config*** End of the configuration.
*** Execute make to start the build or try make help.[rootCentOS8 linux-6.4.11]#make -j 2或者 make -j 8 bzImage ; make -j 8 modules
[rootCentOS8 linux-6.4.11]#time make -j 16 ;date #计时
real 71m7.093s
user 315m20.782s
sys 57m0.485s
Mon Aug 21 01:45:32 CST 2023[rootacentos8 ~]#make modules_install
[rootCentOS8 linux-6.4.11]# ls /lib/modules/
4.18.0-348.el8.x86_64 6.4.11joyce-linux-6-4-11
[rootCentOS8 linux-6.4.11]#du -sh /lib/modules/6.4.11joyce-linux-6-4-11/
4.7G /lib/modules/6.4.11joyce-linux-6-4-11/[rootcentos8 ~]#make install
[rootcentos8 ~]#rebootmake menuconfig 修改完后查看.config文件NTFS已经被修改 4.3.1.4 内核编译说明
1.配置内核选项:
支持“更新”模式进行配置: make help
(a) make config: 基于命令行以遍历的方式配置内核中可配置的每个选项(b) make menuconfig: 基于curses的文本窗口界面© make gconfig: 基于GTK(GNOME) 环境窗口界面(d) make xconfig: 基于QT(KDE)环境的窗口界面
支持“全新配置”模式进行配置
(a)make defconfig: 基于内核为目标平台提供的“默认”配置进行配置(b) make allyesconfig: 所有选项均回答为yes© make allnoconfig: 所有选项均回答为no
2.编译内核 全编译: make [-j #]编译内核的一部分功能: (a)只编译某子目录中的相关代码 cd /usr/src/linux; make dir/(b) 只编译一个特定的模块 cd /usr/src/linux; make dir/file.ko范例: 只为e1000编译驱动:
make drivers/net/ethernet/intel/e1000/e1000.ko3 交叉编译内核
编译的目标平台与当前平台不相同
make ARCHarch name要获取特定目标平台的使用帮助
make ARCHarch_name help示例:
make ARCHarm help4重新编译需要事先清理操作
make clean: 清理大多数编译生成的文件但会保留.config文件等
make mrproper: 清理所有编译生成的文件、config及某些备份文件
make distclean: 包含make mrproper并清理patches以及编辑器备份文件4.3.1.5 卸载内核
删除/usr/src/linux/目录下不需要的内核源码删除/lib/modules/目录下不需要的内核库文件删除/boot目录下启动的内核和内核映像文件更改grub的配置文件删除不需要的内核启动列表 grub2-mkconfig -o /boot/grub2/grub.cfgCentOS 8 还需要删除 /boot/loader/entries/5b85fc7444b240a992c42ce2a9f65db5-新内核版本.conf
5 Busybox
5.1 Busybox介绍 Busybox 最初是由 Bruce Perens 在 1996 年为 Debian GNU/Linux 安装盘编写的。其目标是在一张软盘(存储空间只有1MB多)上创建一个GNU/Linux 系统可以用作安装盘和急救盘
Busybox 是一个开源项目遵循GPL 2协议。Busybox将众多的UNIX命令集合进一个很小的可执行程序中可以用来替代GNU fileutils、shellutils 等工具集。Busybox中各种命令与相应的GNU工具相比所能提供的选项比较少但是也足够一般的应用了。Busybox主要用于嵌入式系统
Busybox 是一个集成了三百多个最常用Linux命令和工具的软件。BusyBox 包含了一些简单的工具例如Is、cat和echo等等还包含了一些更大、更复杂的工具例grep、find、mount以及telnet。有些人将BusyBox 称为 Linux 工具里的瑞士军刀。简单的说BusyBox就好像是个大工具箱它集成压缩了Linux 的许多工具和命令也包含了 Android 系统的自带的shell
定制小型的Linux操作系统: inux内核busybox
官方网站: https://busybox.net/
5.2 Busybox使用
busybox 的编译过程与Linux内核的编译类似
busybox的使用有三种方式
busybox后直接跟命令如 busybox ls直接将busybox重命名如 p busybox tar创建符号链接如 In -s busybox rm
busybox的安装
以上方法中第三种方法最方便但为busybox中每个命令都创建一个软链接相当费事busybox提供自动方法: busybox编译成功后执行make install则会产生一个 install目录其中包含了busybox及每个命令的软链接
5.3 busybox编译安装
[rootcentos7 ~]#yum -y install gcc gcc-c glibc glibc-devel make pcre pcre-devel openssl openssl-devel systemd-devel zlib-devel glibc-static ncurses-devel[rootcentos7 ~]#wget https://busybox.net/downloads/busybox-1.36.1.tar.bz2
[rootcentos7 ~]#tar xvf busybox-1.36.1.tar.bz2
[rootcentos7 ~]#cd busybox-1.36.1/
[rootcentos7 ~]#make menuconfig 按下面选择把busybox编译也静态二进制、不用共享库
#Settings --Build options --[*] Build BusyBox as a static binary (no sharedTibs)
[rootcentos7 ~]#make make install#如果出错执行make clean后重新执行上面命令
[rootcentos7 ~]#mkdir /mnt/sysroot/
[rootcentos7 ~]#cp -a _install/* /mnt/sysroot/6 systemd
6.1 systemd 特性
Systemd: 从 C 7 版本之后开始用 systemd 实现init进程系统启动和服务器守护进程管理器负责在系统启动或运行时激活系统资源服务器进程和其它进程
Systemd新特性
系统引导时实现服务并行启动按需启动守护进程自动化的服务依赖关系管理完全代替xinetd同时采用socket式与D-Bus总线式激活服务socket与服务程序分离向后兼容sysv init脚本使用systemctl 命令管理systemctl命令固定不变不可扩展非由systemd启动的服务systemctl无法与之通信和控制系统状态快照
systemd核心概念: unit
unit表示不同类型的systed对象通过配置文件进行标识和配置;文件中主要包含了系统服务、监听socket、保存的系统快照以及其它与init相关的信息
Unit类型
#查看unit类型
systemctl -t help[rootCentOS7 yum.repos.d]#systemctl -t help
Available unit types:
service
socket
busname
target
snapshot
device
mount
automount
swap
timer
path
slice
scopeservice unit: 文件扩展名为.service用于定义系统服务Target unit: 文件扩展名为.target用于模拟实现运行级别Device unit: .device用于定义内核识别的设备Mount unit:.mount 定义文件系统挂载点Socket unit:.socket 定义进程间通信用的socket文件也可在系统启动时延迟启动服务实现按需启动Snapshot unit: .snapshot管理系统快照Swap unit: .swap用于标识swap设备Automount unit: .automount文件系统的自动挂载点Path unit:.path用于定义文件系统中的一个文件或目录使用常用于当文件系统变化时延时激活服务如: spool 目录
unit的配置文件
/usr/lib/systemd/system;每个服务最主要的启动脚本设置类似于之前的/etc/init.d/
/lib/systemd/system; Ubuntu的对应目录/run/systemd/system; 系统执行过程中所产生的服务脚本比上面目录优先运行
/etc/systemd/system; 管理员建立的执行脚本类似于/etc/rcN.d/sxx的功能比上面目录优先运行6.2 systemctl管理系统服务service unit
命令
systemctl COMMAND name.service例
#启动:相当于service name start
systemctl start name.service#停止: 相当于service name stop
systemctl stop name.service#重启:相当于service name restart
systemctl restart name.service#查看状态: 相当于service name status
systemctl status name.service#禁止自动和手动启动:
systemctl mask name.service#取消禁止
systemctl unmask name.service#查看某服务当前激活与否的状态:
systemctl is-active name.service#查看所有已经激活的服务:
systemctl list-units --type-t service#查看所有服务:
systemctl list-units --type service --all|-a#设定某服务开机自启相当于chkconfig name on
systemctl enable name.service#设定某服务开机禁止启动: 相当于chkconfig name off
systemctl disable name.service#立即启动某服务并设置为开机自启
systemctl enable --now name.service#立即关闭某服务并设置为开机不启动
systemctl disable --now name.service#查看所有服务的开机自启状态相当于chkconfig --list
systemctl list-unit-files --type service#用来列出该服务在哪些运行级别下启用和禁用: chkconfig -list name
Is /etc/systemd/system/*.wants/name.service#查看服务是否开机自启:
systemctl is-enabled name.service#列出失败的服务
systemctl --failed --typeservice#查看服务的依赖关系:
systemctl list-dependencies name.service#杀掉进程:
systemctl kill unitname服务状态
#显示状态
systemctl list-unit-files --type service --allloaded Unit配置文件已处理active(running) 一次或多次持续处理的运行active(exited) 成功完成一次性的配置active(waiting) 运行中等待一个事件inactive 不运行enabled 开机启动disabled 开机不启动static 开机不启动但可被另一个启用的服务激活indirect 重定向到别处
例
#显示所有单元状态
systemctl 或 systemctl list-units#只显示服务单元的状态
systemctl --typeservice#显示sshd服务单元
systemctl -l status sshd.service#验证sshd服务当前是否活动
systemctl is-active sshd#启动停止和重启sshd服务
systemct] start sshd.service
systemctl stop sshd.service
systemctT restart sshd.service#重新加载配置
systemct reload sshd.service#列出活动状态的所有服务单元
systemctl list-units --typeservice#列出所有服务单元
systemctl list-units --typeservice --all#查看服务单元的启用和禁用状态
systemctl list-unit-files --typeservice#列出依赖的单元
systemctl list-dependencies sshd#验证sshd服务是否开机启动
systemctl is-enabled sshd#禁用network使之不能自动启动但手动可以
systemctl disable network#启用network
systemct] enabe network#禁用network使之不能手动或自动启动
systemctl mask network#启用network
systemct] unmask network6.3 service unit文件格式
/etc/systemd/system: 系统管理员和用户使用
/usr/lib/systemd/system: 发行版打包者使用帮助参考:
systemd.directives (7)systemd.unit(5)systemd.service(5) systemd.socket(5)systemd.target(5)systemd.exec(5)
unit 格式说明:
以“#”开头的行后面的内容会被认为是注释相关布尔值1、yes、on、true 都是开启0、no、off、false 都是关闭时间单位默认是秒所以要用毫秒 (ms)分钟 (m) 等须显式说明
service unit file文件通常由三部分组成**
[Unit]: 定义与Unit类型无关的通用选项;用于提供unit的描述信息、unit行为及依赖关系等
[Service]: 与特定类型相关的专用选项; 此处为Service类型
[Install]: 定义由“systemctl enable”以及”systemctl disable”命令在实现服务启用或禁用时用到的一些选项Unit段的常用选项:
Description: 描述信息
After: 定义unit的启动次序表示当前unit应该晚于哪些unit启动其功能与Before相反
Requires: 依赖到的其它units强依赖被依赖的units无法激活时当前unit也无法激活
Wants:依赖到的其它units弱依赖
Conflicts: 定义units间的冲突关系Service段的常用选项:
Type:定义影响ExecStart及相关参数的功能的unit进程启动类型simple: 默认值这个daemon主要由ExecStart接的指令串来启动启动后常驻于内存中forking: 由ExecStart启动的程序透过spawns延伸出其他子程序来作为此daemon的主要服务。原生父程序在启动结束后就会终止oneshot: 与simple类似不过这个程序在工作完毕后就结束了不会常驻在内存中dbus: 与simple类似但这个daemon必须要在取得一个D-Bus的名称后才会继续运作.因此通常也要同时设定BusNname 才行onotify: 在启动完成后会发送一个通知消息。还需要配合 NotifyAccess 来让Systemd 接收消息idle: 与simple类似要执行这个daemon必须要所有的工作都顺利执行完毕后才会执行。这类的daemon通常是开机到最后才执行即可的服务EnvironmentFile:环境配置文件
ExecStart:指明启动unit要运行命令或脚本的绝对路径
ExecStartPre:ExecStant前运行
ExecStartPostExecStart后运行
ExecStop:指明停止unit要运行的命令或脚本
Restart: 当设定Restart1 时则当次daemon服务意外终止后会再次自动启动此服务
PrivateTmp: 设定为yes时会在生成/tmp/systemd-private-UUID-NAME.service-XXXXX/tmp/目录Install段的常用选项:
Alias: 别名可使用systemctl command Alias.service
RequiredBy: 被哪些units所依赖强依赖
WantedBy:被哪些units所依赖弱依赖
Also: 安装本服务的时候还要安装别的相关服务注意:对于新创建的unit文件或者修改了的unit文件要通知systemd重载此配置文件而后可以选择重启
systemctl daemon-reToad范例: 服务Unit文件——http
[unit]
DescriptionThe Nginx HTTP Server daemon # 描述信息
Afternetwork.target remote-fs.target nss-lookup.target # 指定启动nginx之前需要其他的其他服务如network.target等[service]
# Type为服务类型仅启动一个主进程的服务为simple需要启动若干子进程的服务为forking
Typeforking# 设置执行systemctl start nginx后需要启动的具体命令
Execstart/usr/ocal/nginx/sbin/nginx# 设置执行systemctl reload nginx后需要执行的具体命令
ExecReToad/usr/local/nginx/sbin/nginx -s reload# 设置执行systemctl stop nginx后需要执行的具体命令
Execstop/bin/kill -s OUIT ${MAINPID}[Install]
# 设置在什么模式下被安装设置开机启动的时候需要
wantedBymulti-user.target范例: 服务Unit文件示例——tomcat
vim /usr/lib/systemd/system/tomcat.service
[unit]
Descriptionjava tomcat project
AftersysTog.target network.target[service]
Typeforking
EnvironmentFile/usr/local/tomcat/conf/tomcat.conf
Execstart/usr/local/tomcat/bin/startup.sh
Execstop/usr/local/tomcat/bin/shutdown.sh
PrivateTmptrue
Usertomcat[Install]
wantedBymulti-user.target**范例: 服务Unit文件示例——**bak
vim /etc/systemd/system/bak.service
[unit]
Descriptionbackup /etc
Requiresatd.service[service]
Typesimple
Execstart/bin/bash -c echo /data/bak.sh | at now[Install]
WantedBymulti-user.target
systemctl daemon-reload
systemctl start bak范例: Ubutun实现开机自动运行程序
[rootubuntu1804 ~]#vim /etc/rc.local
[rootubuntu1804 ~]#cat /etc/rc.local
#!/bin/bash
echo -e E[31;1mstarting test service E[Om
sleep 10
[rootubuntu1804 ~]#chmod x /etc/rc.local6.4 运行级别
target units: 相当于CentOS 6之前的runlevelunit配置文件: target
ls /usr/lib/systemd/system/*.target
systemctl list-unit-files --type target --a77和运行级别对应关系
0 runlevel0.targetpoweroff.target
1 runlevel1.targetrescue.target
2 runlevel2.targetmulti-user.target
3 runlevel3.targetmulti-user.target
4 runlevel4.targetmulti-user.target
5 runlevel5.targetgraphical.target
6 runlevel6.targetreboot.target查看依赖性:
systemct1 1ist-dependencies graphical.target级别切换: 相当于 init N
systemct1 isolate name.target进入默认target
systemct7 defau7t范例:
#切换至字符模式
systemct] isolate multi-user.target注意:只有/lib/systemd/system/*.target文件中Allowlsolateyes 才能切换(修改文件需执行systemd daemon-reload才能生效)
获取默认运行级别:相当于查看 /etc/inittab
systemct1 get-defaut修改默认级别: 相当于修改 /etc/inittab
systemct1 set-default name.target范例:
[rootcentos8 ~]#systemctl set-default multi-user.target
[rootcentos8 ~]#ls -l /etc/systemd/system/default.target
lrwxrwxrwx. 1 root root 37 NoV 7 19:32 /etc/systemd/system/default.target - /1ib/systemd/system/multi-user.target切换至紧急救援模式
systemct1 rescue切换至emergency模式
systemctl emergency说明: rescue.target 比emergency 支持更多的功能例如日志等
传统命令initpoweroffhaltreboot都成为systemctl的软链接
#关机
systemct1 halt、systemct1 poweroff#重启:
systemctl reboot#挂起:
systemct1 suspend#休眠:
systemct7
hibernate
#休眠并挂起:
systemct1 hybrid-sTeep范例: 禁用ctrlaltdelete 重启快捷键
[rootcentos8 ~]#ls -l /1ib/systemd/system/ctrl-alt-del.target
lrwxrwxrwx. 1 root root 13 May 23 2019 /1ib/systemd/system/ctrl-alt-del.target - reboot.target
[rootcentos8 ~]#systemct1 mask ctrl-alt-de1.target
Created symlink /etc/systemd/system/ctr]-alt-del.target - /dev/nul1
[rootcentos8 ~]#init q
[rootcentos8 ~]#systemctl daemon-reload6.5 Centos 7之后版本引导顺序 UEFi或BIOS初始化运行POST开机自检 选择启动设备 引导装载程序,centos7是grub2,加载装载程序的配置文件 /etc/grub.d/ /etc/default/grub /boot/grub2/grub.cfg 加载initramfs驱动模块 加载内核选项 内核初始化centos7使用systemd代替init 执行initrd.target所有单元包括挂载/etc/fstab 从initramfs根文件系统切换到磁盘根目录 systemd执行默认target配置配置文件/etc/systemd/system/default.target systemd执行sysinit.target初始化系统及basic.target准备操作系统 systemd启动multi-user.target下的本机与服务器服务 systemd执行multi-user.target下的/etc/rc.d/rc.local Systemd执行multi-user.target下的getty.target及登录服务 systemd执行graphical需要的服务
通过systemd-analyze 工具可以了解启动的详细过程
[rootCentOS8 ~]#systemd-analyze blame40.827s dnf-makecache.service6.374s plymouth-quit-wait.service5.407s cockpit-motd.service3.263s unbound-anchor.service2.570s mysqld.service1.543s tuned.service1.443s postfix.service1.373s systemd-udev-settle.service1.329s vdo.service1.038s sssd.service796ms polkit.service777ms ModemManager.service679ms initrd-switch-root.service674ms lvm2-monitor.service553ms NetworkManager-wait-online.service516ms avahi-daemon.service429ms NetworkManager.service426ms smartd.service425ms dracut-initqueue.service258ms autofs.service202ms cups.service180ms packagekit.service175ms accounts-daemon.service171ms udisks2.service168ms systemd-udev-trigger.service163ms bluetooth.service159ms systemd-logind.service143ms systemd-tmpfiles-clean.service133ms systemd-udevd.service125ms user0.service116ms sysroot.mount100ms sshd.service100ms rsyslog.service83ms initrd-parse-etc.service82ms gdm.service74ms systemd-tmpfiles-setup-dev.service69ms systemd-vconsole-setup.service68ms cockpit.service68ms sysstat-summary.service68ms systemd-modules-load.service61ms auditd.service59ms systemd-journald.service58ms nis-domainname.service57ms kmod-static-nodes.service56ms sys-kernel-debug.mount56ms boot.mount53ms dev-disk-by\x2duuid-80ee59c8\x2db184\x2d4f49\x2d9039\x2d5150257143b8.swap53ms systemd-remount-fs.service48ms plymouth-switch-root.service47ms systemd-fsckdev-disk-by\x2duuid-54ead45a\x2d7577\x2d4b54\x2d9de2\x2d501aef04207a42ms dracut-pre-pivot.service41ms dracut-cmdline.service41ms data.mount40ms dev-hugepages.mount37ms iscsi-shutdown.service36ms dev-mqueue.mount33ms systemd-user-sessions.service33ms systemd-journal-flush.service33ms systemd-tmpfiles-setup.service31ms rtkit-daemon.service40.827s dnf-makecache.service6.374s plymouth-quit-wait.service5.407s cockpit-motd.service3.263s unbound-anchor.service2.570s mysqld.service1.543s tuned.service1.443s postfix.service1.373s systemd-udev-settle.service1.329s vdo.service1.038s sssd.service796ms polkit.service777ms ModemManager.service679ms initrd-switch-root.service674ms lvm2-monitor.service553ms NetworkManager-wait-online.service516ms avahi-daemon.service429ms NetworkManager.service426ms smartd.service425ms dracut-initqueue.service258ms autofs.service202ms cups.service180ms packagekit.service175ms accounts-daemon.service171ms udisks2.service168ms systemd-udev-trigger.service163ms bluetooth.service159ms systemd-logind.service143ms systemd-tmpfiles-clean.service133ms systemd-udevd.service125ms user0.service116ms sysroot.mount100ms sshd.service100ms rsyslog.service83ms initrd-parse-etc.service82ms gdm.service74ms systemd-tmpfiles-setup-dev.service69ms systemd-vconsole-setup.service68ms cockpit.service68ms sysstat-summary.service68ms systemd-modules-load.service61ms auditd.service59ms systemd-journald.service58ms nis-domainname.service57ms kmod-static-nodes.service56ms sys-kernel-debug.mount56ms boot.mount53ms dev-disk-by\x2duuid-80ee59c8\x2db184\x2d4f49\x2d9039\x2d5150257143b8.swap53ms systemd-remount-fs.service48ms plymouth-switch-root.service47ms systemd-fsckdev-disk-by\x2duuid-54ead45a\x2d7577\x2d4b54\x2d9de2\x2d501aef04207a42ms dracut-pre-pivot.service41ms dracut-cmdline.service41ms data.mount40ms dev-hugepages.mount37ms iscsi-shutdown.service36ms dev-mqueue.mount33ms systemd-user-sessions.service33ms systemd-journal-flush.service33ms systemd-tmpfiles-setup.service31ms rtkit-daemon.service30ms sysstat.service30ms systemd-random-seed.service28ms systemd-sysctl.service22ms import-state.service20ms dracut-pre-udev.service19ms plymouth-read-write.service18ms initrd-cleanup.service17ms plymouth-start.service17ms cockpit.socket15ms plymouth-quit.service14ms proc-sys-fs-binfmt_misc.mount14ms cockpit-wsinstance-https-factory.socket14ms systemd-fsck-root.service13ms systemd-rfkill.service12ms sys-fs-fuse-connections.mount11ms cockpit-wsinstance-http.socket9ms systemd-update-utmp.service9ms user-runtime-dir0.service7ms systemd-update-utmp-runlevel.service6ms dracut-shutdown.service5ms initrd-udevadm-cleanup-db.service5ms sysstat-collect.service2ms sys-kernel-config.mount1ms cockpit-wsinstance-http-redirect.socket
lines 61-84/84 (END)30ms sysstat.service30ms systemd-random-seed.service28ms systemd-sysctl.service22ms import-state.service20ms dracut-pre-udev.service19ms plymouth-read-write.service18ms initrd-cleanup.service17ms plymouth-start.service17ms cockpit.socket15ms plymouth-quit.service14ms proc-sys-fs-binfmt_misc.mount14ms cockpit-wsinstance-https-facto14ms systemd-fsck-root.service13ms systemd-rfkill.service
lines 61-74/84 87%30ms sysstat.service30ms systemd-random-seed.service28ms systemd-sysctl.service22ms import-state.service20ms dracut-pre-udev.service19ms plymouth-read-write.service18ms initrd-cleanup.service17ms plymouth-start.service17ms cockpit.socket15ms plymouth-quit.service14ms proc-sys-fs-binfmt_misc.mount14ms cockpit-wsinstance-https-factory.socket14ms systemd-fsck-root.service13ms systemd-rfkill.service12ms sys-fs-fuse-connections.mount11ms cockpit-wsinstance-http.socket9ms systemd-update-utmp.service9ms user-runtime-dir0.service7ms systemd-update-utmp-runlevel.service6ms dracut-shutdown.service5ms initrd-udevadm-cleanup-db.service5ms sysstat-collect.service2ms sys-kernel-config.mount1ms cockpit-wsinstance-http-redirect.socket
lines 61-84/84 (END)#或xml文件
[rootCentOS8 ~]#systemd-analyze plot boot.xml
然后传到win下用浏览器打开[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-xvJxmwXs-1692688111234)(C:\Users\HUIO\AppData\Roaming\Typora\typora-user-images\image-20230822120113748.png)]
6.6 设置内核参数
设置内核参数只影响当次启动
启动时到启动菜单按e键找到在linux 开头的行后添加systemd.unitdesired.target
例如 systemd.unitemergency.target 或 systemd.unitrescue.target6.7 破解 CentOS 7和8的 root 密码
方法一
启动时任意键暂停启动
按e键进入编辑模式
将光标移动linux 开始的行(C7是Linux16那行 )添加内核参数rd.break
按ctrl-x启动
mount -o remount,rw /sysroot
chroot /sysroot
passwd root#如果SELinux是启用的,才需要执行下面操作如查没有启动不需要执行
touch /.autorelabelexit
reboot方式二
启动时任意键暂停启动
按e键进入编辑模式
将光标移动linux 开始的行改为rw init/sysroot/bin/sh
按ctrl-x启动
chroot /sysroot
passwd root#如果SELinux是启用的,才需要执行下面操作,如查没有启动,不需要执行
touch /.autorelabelexit
reboot6.8 实现GRUB2安全
#添加grub密码
[rootCentOS8 ~]#grub2-setpassword
Enter password:
Confirm password:
#查看文件
[rootCentOS8 ~]#ll /boot/grub2/
total 340
-rw-r--r--. 1 root root 64 May 30 23:36 device.map
drwxr-xr-x. 2 root root 4096 May 30 23:36 fonts
-rw-r--r--. 1 root root 6590 Jul 25 15:05 grub.cfg
-rw------- 1 root root 1024 Aug 16 13:51 grubenv
drwxr-xr-x. 2 root root 12288 May 30 23:36 i386-pc
-rw-r--r-- 1 root root 309444 Aug 18 21:48 logo.xpm
-rw------- 1 root root 298 Aug 22 12:21 user.cfg
[rootCentOS8 ~]#cat /boot/grub2/user.cfg
GRUB2_PASSWORDgrub.pbkdf2.sha512.10000.0DCB0C5B0F0A9B3021C99E920A0731164C713BCA004314B049811590E32A84348686B899E6D161D11D6C663C10A0C33100BE582B7BA5CF39C5919E845D9AEA6B.4AF8E233565BF8508115991D41FCCB2B3387E35807D5BE510744A86AD64F7C0CB79CE1166AFAB1186E957D10060DFAD1CA6B57C067815CE744175070E5FD501D
#清空grub密码
[rootcentos8 ~]#at /dev/null /boot/grub2/user.cfg6.9 修复GRUB2
GRUB2: Centos 78及ubuntu1804都使用
引导提示时可以使用命令行界面可从文件系统引导
主要配置文件: /boot/grub2/grub.cfg修复配置文件: grub2-mkconfig /boot/grub2/grub.cfg修复grub
grub2-install /dev/sda #BIOS环境
grub2-insta77 #UEFI环境调整默认启动内核
#以下命令是修改 /boot/grub2/grubenv 实现
grub2-set-default 0 #适合C7因为C8配置文件中不再存储内核对应的数字不知道0、1对应的是哪个内核或者vim /etc/default/grub
GRUB_DEFAULT0[rootCentOS8 ~]#cat /boot/grub2/grubenv #默认启动内核
# GRUB Environment Block
saved_entry34f09f8df29847998143d560b2af24fb-4.18.0-348.el8.x86_64 #修改为需要的内核即可适合C8
kerneloptsrootUUIDf2c173be-7848-43e9-9d0b-da0f1841f93f ro resumeUUID80ee59c8-b184-4f49-9039-5150257143b8 rhgb quiet net.ifnames0
boot_success1
boot_indeterminate0
########################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################################[rootCentOS8 ~]#cd
[rootCentOS8 ~]#ls /boot/loader/entries/ #查看所有内核
34f09f8df29847998143d560b2af24fb-0-rescue.conf
34f09f8df29847998143d560b2af24fb-4.18.0-348.el8.x86_64.conf6.10 故障排错实战案例
6.10.1 实战案例1: centos 78 破坏MBR后进行恢复
dd if/dev/zero of/dev/sda bs1 count446
光盘进入救援模式
grub2-instal1 --root-directory/mnt/sysimage /dev/sda6.10.2 实战案例2: entos 78删除/boot/grub2/*所有内容进行恢复
#光盘进入救援模式
chroot /mnt/sysimage
grub2-install /dev/sda
grub2-mkconfig -o /boot/grub2/grub.cfg6.10.3 实战案例3: Centos 78 删除/boot/下所有文件后进行恢复
#1 光盘救援模式下安装grub2
特别说明: centos8 必须先grub再安装kernel,否则安装kernel-core时会提示grub出错
chroot /mnt/sysimage
mount /dev/sr0 /mnt
grub2-install /dev/sda#2 安装kernel
#Centos 7
rpm -ivh /mnt/Packages/kernel-3.10.0-1062.e17.x86_64.rpm --force
#Centos 8
rpm -ivh /mnt/Baseos/Packages/kernel-core-4.18.0-147.e18.x86_64.rpm --force#3 修复grub配置文件
生成grub2.cfg文件
grub2-mkconfig -o /boot/grub2/grub.cfg#4 退出重启
exit
exit
