Terminal (OS X)

How to Repair GRUB2 When Ubuntu Won’t Boot

Ubuntu and many other Linux distributions use the GRUB2 boot loader. If GRUB2 breaks—for example, if you install Windows after installing Ubuntu, or overwrite your MBR—you won’t be able to boot into Ubuntu.

You can easily restore GRUB2 from a Ubuntu live CD or USB drive. This process is different from restoring the legacy GRUB boot loader on older Linux distributions.

This process should work on all versions of Ubuntu. It’s been tested on Ubuntu 16.04 and Ubuntu 14.04.

The Graphical Method: Boot Repair

Boot Repair is a graphical tool that can repair GRUB2 with a single click. This is the ideal solution to boot problems for most users.

If you have the media you installed Ubuntu from, insert it into your computer, restart, and boot from the removable drive. If you don’t, download a Ubuntu live CD and burn it to a disc or create a bootable USB flash drive.

When Ubuntu boots, click “Try Ubuntu” to get a usable desktop environment.

Ensure you have an Internet connection before continuing. You may need to choose a Wi-Fi network and enter its passphrase.

Open a Terminal window from the Dash and run the following commands to install and launch Boot Repair:

sudo apt-add-repository ppa:yannubuntu/boot-repair sudo apt-get update sudo apt-get install -y boot-repair boot-repair

The Boot Repair window will automatically scan your system after you run the boot-repair command. After it scans your system, click the “Recommended repair” button to repair GRUB2 with a single click.

You can choose to use the advanced options here, but Ubuntu’s wiki recommends you not use the advanced options unless you know what you’re doing. The recommended repair option can fix most…

How to Create and Use Symbolic Links (aka Symlinks) on a Mac

Symbolic links, also known as symlinks, are special files that point to files or directories in other locations on your system. You can think of them like advanced aliases and here’s how to use them in MacOS.

Symbolic links are similar to aliases, except they work in every application on your Mac—including in the Terminal. They’re particularly useful when apps don’t want to work correctly with a regular alias. On macOS, you create symbolic links in the Terminal using the ln utility. You can’t create them in the Finder. Symbolic links in macOS work similarly to symbolic links in Linux, because both are Unix-like operating systems. Symbolic links in Windows work a bit differently.

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What Are Symbolic Links?

In macOS, you can create regular aliases in the Finder. Aliases point at files or folders, but they’re more like simple shortcuts.

A symbolic link is a more advanced type of alias that works in every application on the system, including command-line utilities in the terminal. A symbolic link you create appears to apps to be the same as the original file or folder it’s pointing at—even though it’s just a link.

For example, let’s say you have a program that needs its files stored at /Library/Program. But you want to store those files somewhere else on the system—for example, in /Volumes/Program. You can move the Program directory to /Volumes/Program, and then create a symbolic link at /Library/Program pointing to /Volumes/Program. The program will try to access its folder at /Library/Program, and the operating system will redirect it to /Volumes/Program.

This is entirely transparent to the macOS operating system and the applications you use. If you browse to the /Library/Program directory in the Finder or any other application, it will appear to contain the files inside /Volumes/Program.

In addition to symbolic links, which are sometimes called “soft links”, you can instead create “hard links”. A symbolic or soft link points to a path in the file system. For example, let’s say you have a symbolic—or soft—link from /Users/example pointing to /opt/example. If you move the file at /opt/example, the link at /Users/example will be broken. However, if you create a hard link, it will actually point to the underlying inode on the file system. So, if you created a hard link from /Users/example pointing to /opt/example and later moved /opt/example, the link at /Users/example would still point to the file, no matter where you moved it. The hard link works at a lower level.

You should generally use standard symbolic…