# Task1参考答案

## 什么是shell

![操作系统架构](https://www3.nd.edu/~pbui/teaching/cse.30341.fa17/static/img/house.png)

## 常用的shell命令

* 文件与目录

```bash
ls
```

列出当前目录内容

```bash
cd /home/
```

进入home目录

* 安装软件

```bash
yum install vim
```

安装vim

## shell脚本编写

* 变量

第一个脚本的编写

1. 编辑run.sh，vim run.sh
2. 按下"i"进入编辑模式,输入:

```bash
NAME="Hello"
echo $NAME
```

1. 保存，:wq
2. 执行，bash run.sh

* 循环

```bash
for ((i = 0 ; i < 100 ; i++)); do
  echo $i
done
```

* 条件判断

```bash
if [[ X ]] && [[ Y ]]; then
  ...
fi
```

* 函数

```bash
function sayHello() {
    echo "hello $1"
}
sayHello "John"
```


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