跳至主要内容

Class 3

一. shell脚本

  1. 基本语法
    •  #!/bin/bash    声明解释该脚本的程序，使用后可使用bash内建的指令
    • #!被称为魔数    魔数后应指定运行该脚本所需程序的完整路径
  2. 特点
  3. shell脚本解释器
    • bash  Linux内建的shell，BourneAgain Bash缩写，内部命令40个
      • 包含自身帮助
      • 查找匹配，命令文件名补全
      • 可用方向键查阅和快速修改
    • sh  是Bourne Shell的缩写，sh 是Unix 标准默认的shell
    • ash  占用系统资源最少的一个小shell，只包含24个内部命令,使用不方便
    • csh  内部52个命令，指向/bin/tcsh
    • ksh  与商业版相同，体会商业版乐趣
  4. 不适用shell
    • 工作量大，跨平台，安全性，GUI,直接操作系统硬件
    • 需要使用库或是遗留下来的老代码
    • 私人闭源的项目
  5. shell变量规范
    • your_name="shilizhuang"
      echo ${your_name}
    • 变量字母开头，仅包含字母、数字、下划线
二. 程序设计预言
  1. 编译型语言
    • 程序运行之前有一个单独的编译过程
    • Fortran、Ada、Pascal、C、C++和Java    需要预先将写好的源代码(source code)转换成目标代码(object code)，这个过程被称作“编译”
      • 优点：运行程序时，直接读取目标代码(object code)，由于非常接近计算机              底层，执行效率很高
      • 缺点：多半运作于底层，所处理的是字节、整数、浮点数或是其他机器层级            的对象，实现简单的功能需要大量复杂的代码
  2. 解释型语言
    • 运行的时候边转化为机器语言，因此速度不快
      • 也被称为“脚本语言”
      • 运行在比编译型语言高的层级，能够轻易处理文件与目录之类的对象

三. 环境变量

  1. 重定向（可用于备份）
    • >输出重定向
    • >>追加到末尾
    • <输入重定向
    • <<内联输入重定向

四. 自己了解的内容

  1. 引导
    • grub(目前出到grup2)
    • NT
  2. yum命令
  3. 两个案例练习




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