# 管道及I/O重定向

## 输出重定向

![](https://github.com/clay-wangzhi/wiki/tree/ad8da33d2cec6c9b4eefadb893708ef16537ed64/Linux/基础/images/biaozhun.png) 输出重定向（覆盖）

```
date > a.txt
```

输出重定向（追加）

```
date 1>> a.txt
```

错误输出重定向

```
ls /home/ /aa >> a.txt 2>b.txt
```

正确和错误都输入到相同位置

```
ls /home/ /aa &> a.txt 
ls /home/ /aa > a.txt 2>&1
```

重定向到空设备/dev/null

```
ls /home/ /aa &> /dev/null
```

## 输入重定向

```
grep 'root' < /etc/passwd
```

```
mysql -uroot -p123 < aa.sql
```

## 总和应用

```
cat > a.txt <<EOF
> 11
> 22
> EOF
```


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