计算机速度变慢(slow down)是不争的事实。有时这是由于磨损造成的，但也可能是简单的事情，就像您的硬盘驱动器充满不再需要的文件一样。或意外删除的重要操作系统文件。
发生这种情况时，是时候考虑重新安装操作系统了。这是一个巨大的痛苦，因为它不是一个短暂的过程，但在 macOS 的情况下，这是一个简单的过程。你需要一个互联网(Internet)连接，所以不要考虑在公共汽车或任何东西上这样做。
这是我一直想做的事情，但
拖延症(Procrastination)是我的朋友。但是今天，为了本文的目的，我决定完成它。
第一步 - 备份所有基本文件(Step One –
Backup All Essential Files)
这始终是重新安装操作系统之前的第一步。要删除所有不需要的文件，然后将其余文件备份到云存储、USB记忆棒或可移动硬盘驱动器上。
请记住(Remember)同时备份您的 iTunes 资料库、iMovie 数据库和照片(Photos)数据库。这些可以拖到便携式存储设备上，然后在此过程结束后再次拖回计算机上。
如果您使用 Time Machine，则此备份过程非常简单。
第二步 - 关闭 FileVault(Step Two – Turn
Off FileVault)
启用 FileVault(FileVault)会阻止您重新格式化和重新安装硬盘驱动器。所以进入System Preferences–>Security & Privacy并将其关闭。这可能需要长达 30 分钟，因此请耐心等待。去煮咖啡什么的。
第三步 - 您是否加密了启动盘？(Step Three –
Have You Encrypted The Start-Up Disk?)
出于安全原因，您应该从一开始就加密您的启动盘(encrypted your startup disk)。这样做的一个小缺点是，如果您忘记了加密密码，您将永远无法再次解锁它，也永远无法重新安装 macOS。
相信(Trust)我，我是从过去非常痛苦的经历中说出来的。
假设您知道密码，请重新启动计算机，同时按住CMD + R键。然后，这将向您显示上面的挂锁屏幕（我必须拍摄，因为在这个阶段我不能做截图）。
输入您的密码，然后屏幕将更改为您显示此密码。再一次(Again)，我不得不用我的 iPhone 拍照，所以对质量不太完美表示歉意。
如果您不知道您的密码，那么您就非常不走运，因为即使Apple也不会为您解锁它。
第四步 - 擦除硬盘驱动器的内容(Step Four –
Erase The Contents Of The Hard Drive)
从上面的菜单中可以看到，有一个名为“磁盘工具(Disk Utility)”的选项。选择它，然后选择安装操作系统的磁盘。就我而言，只有一个磁盘，但如果您是双引导，您将拥有多个磁盘。
现在单击“擦除”，将弹出一个小框，询问您新格式化驱动器的所需名称以及文件格式类型（APFS）。我建议让它们保持原样。
擦除实际上需要几秒钟（无论如何根据我的经验）。完成后，磁盘的“已使用”部分应该很小（在我的例子中为 20KB）。此时，您计算机上的所有内容都已消失。
关闭磁盘实用程序(Disk Utility)窗口，您将被弹回实用程序(Utilities)屏幕。
第五步 - 选择您喜欢的重新安装选项(Step Five –
Choose Your Preferred Reinstalling Option)
现在，实用程序窗口中实际上有两个选项可供您选择。
第一个是Time Machine备份。如果您有定期使用Time Machine(Time Machine)备份的习惯，并且有一天，您不小心删除了一大堆系统文件，您可以将计算机回滚到前一天的Time Machine备份。(Time Machine)这相当于在Windows PC上执行系统还原。(System Restore)
但我不使用Time Machine（我手动备份）。因此，对于我和像我这样的其他人来说，唯一的其他选择是选择“重新安装 macOS”选项。因此，继续并单击它，然后在提示您时单击“继续”。
第六步——假装阅读用户协议(Step Six –
Pretend To Read The User Agreement)
现在将要求您阅读用户协议。做其他人做的事，假装你读过它，然后点击“同意”。别担心，
苹果(Apple)永远不会知道。
现在选择一个磁盘来安装操作系统。就我而言，只有一个磁盘。选择它并继续。
现在将开始重新安装过程。
在此过程中，计算机将重新启动几次，并且可能需要一个小时或更长时间才能完成。好消息是它从现在开始可以自己做所有事情，所以你可以在此期间去做其他事情。你不会被困在屏幕上，看着你的生活溜走。
第七步 - 重新设置一切(Step Seven –
Set Everything Back Up Again)
重新安装系统后，您将不得不开始将事物恢复原状的繁琐过程。这将包括：
- 开启防火墙。
- 打开 FileVault。
- 重新加密启动盘。
- 重新安装您的应用程序。
- 将重要文件从备份中带回计算机。
- 添加屏幕锁定 PIN 码。
本质上，您必须通过系统偏好设置(System Preferences)并一一检查每一件事。计算机现在已恢复出厂设置，因此您之前所做的任何调整和自定义都将消失。
有一个很棒的指南叫做Hardening macOS [note link not working]，它为您提供了一个巨大的安全预防措施列表（超过 40 个），您应该在全新安装 macOS 时执行。我强烈建议您参考它并尽可能多地做。其中一些听起来可能有点矫枉过正，但你永远不能太小心。
How To Hard Reset a Mac OS X Computer & Reinstall The OS
It’s a fact оf life that computers slow down. Sometimes it’s due to wear and tear but it can also be something as simple as your hard-drive filling up with files that are no longer needed. Or essential operating system files that are accidentally deleted.
When this happens, it’s time to consider reinstalling the operating system. It is a monumental pain in the neck as it is not a short process, but in the case of macOS, it is an easy process. You need an Internet connection though so don’t think about doing this on the bus or anything.
This is something I have been meaning to do for a while but
Procrastination is my friend. But today, for the purposes of this article, I
have decided to get it done.
Step One –
Backup All Essential Files
This is always the first step before reinstalling an operating system. To delete all unneeded files then backup the rest either on cloud storage, a USB stick, or a removable hard drive.
Remember to also backup your iTunes library, your iMovie
database, and your Photos database. These can be dragged onto portable storage
and then dragged back onto the computer again later when this process is over.
If you use Time Machine, then this backup process is very
easy.
Step Two – Turn
Off FileVault
Having FileVault on stops you from reformatting and reinstalling the hard drive. So go into System Preferences–>Security & Privacy and turn it off. This can take up to 30 minutes so be patient. Go make a coffee or something.
Step Three –
Have You Encrypted The Start-Up Disk?
For reasons of security, you should have encrypted your startup disk from the very beginning. The slight downside to this is that if you forget the encryption password, you can never unlock it ever again and can never reinstall macOS.
Trust me, I am speaking from very bitter past experience
here.
Assuming you know your password, restart the computer and at
the same time, hold down the CMD + R keys. This will then show you the padlock
screen above (which I had to photograph since I can’t do screenshots at this
stage).
Enter your password and the screen will then change to show
you this. Again, I had to take a photo with my iPhone so apologies for the
not-so-perfect quality.
If you don’t know your password then you are seriously out of
luck as not even Apple will unlock it for you.
Step Four –
Erase The Contents Of The Hard Drive
As you can see from the menu above, there is an option called “Disk Utility”. Choose that and then select the disk where the operating system is installed on. In my case, there is only one disk but if you are dual-booting, you will have more than one.
Now click “Erase” and a small box will pop up asking you for
the desired name of the newly formatted drive as well as the file format type
(APFS). I would recommend leaving them as they are.
Erasing takes literally seconds (in my experience anyway). When it is done, the “Used” part of the disk should be minuscule (in my case, 20KB). At this point, everything on your computer is gone.
Close the Disk Utility window and you’ll be bounced back to
the Utilities screen.
Step Five –
Choose Your Preferred Reinstalling Option
Now there are actually two options in the Utilities window
you can choose from.
The first is the Time Machine backup. If you are in the habit of regularly backing up with Time Machine, and one day, you accidentally delete a whole bunch of system files, you could just roll the computer back to a Time Machine backup from, say, the day before. This would be the equivalent of doing a System Restore on a Windows PC.
But I don’t use Time Machine (I manually backup). So for me
and others like me, the only other option is to choose the “Reinstall macOS”
option. So go ahead and click on that, and click “Continue” when it prompts
you.
Step Six –
Pretend To Read The User Agreement
You will now be asked to read the user agreement. Do what
everyone else does and pretend you read it and click “Agree”. Don’t worry,
Apple will never know.
Now choose a disk to install the operating system on. In my
case, there is only one disk. Choose it and continue.
The re-installation process will now begin.
The computer will restart several times during the process
and can take up to an hour or more to finish. The nice thing is that it does
everything by itself from now on so you can go off and do something else in the
meantime. You’re not stuck staring at the screen watching your life slip away.
Step Seven –
Set Everything Back Up Again
Once the system has been reinstalled, you will have to begin
the tedious process of putting things back to the way they were. This will
include :
- Switching
on the Firewall.
- Switching
on FileVault.
- Re-encrypting
the startup disk.
- Reinstalling
your apps.
- Bringing
essential files back onto the computer from your backups.
- Adding
a screen lock PIN code.
Essentially you have to go through System Preferences and check each thing one by one. The computer is now back to factory settings so any tweaks and customizations you previously made will be gone.
There is a great guide called Hardening macOS [note link not working] which gives you a huge list (more than 40) of security precautions you should carry out with a fresh install of macOS. I highly recommend you refer to it and do as many of them as possible. Some of it might sound like overkill but you can never be too careful.
