brew
brew使用时提示error：not writable
```
liyongdeMacBook-Pro:~ ly$ brew update
Error: /usr/local is not writable. You should change the
ownership and permissions of /usr/local back to your
user account:
sudo chown -R $(whoami) /usr/local
在终端使用sudo chown -R $(whoami) /usr/local回车后输入电脑密码即可
```base
#获取执行权限
chmod 777 ~/.test.sh
chmod 777 绝对路径
#编辑文件
sudo nano 文件的绝对路径
mac 电脑清理-2017-3-25
43.16 G—60.6G—69.77G
缓存：~/Library/Caches/
/Users/ly/Library/logs
/Users/ly/Library/Developer
/Users/ly/Library/Containers
/Users/ly/Library/Developer/CoreSimulator/Devices模拟器
/Users/ly/Library/Developer/Xcode/Archives 打包文件
/Users/ly/Library/Developer/Xcode/DerivedData
/Users/ly/Library/Developer/Xcode/iOS DeviceSupport iOS模拟器版本
