# 使用sudo在文件中添加内容

在shell命令行中，有时候需要给一个`root`用户的文件添加内容，但是当前shell执行用户是普通用户身份，则会出现如下执行权限不足的报错

```bash
$ echo "export PATH=$PATH:/opt/bin" >> /etc/profile
-bash: /etc/profile: Permission denied
```

解决的方法有以下两种：

* 使用`sudo tee -a`命令，通过管道传递需要添加的内容给`tee`，由于`tee`通过`sudo`执行，就具有权限写入文件

```bash
echo "export PATH=$PATH:/opt/bin" | sudo tee -a /etc/profile
```

* 使用`sudo bash -c`命令，使得整个shell都具有`root`用户权限

```bash
sudo bash -c "echo 'export PATH=$PATH:/opt/bin' >> /etc/profile"
```

## 参考

* [How to append to a file as sudo?](http://superuser.com/questions/136646/how-to-append-to-a-file-as-sudo)


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