Symbolic links are quite possibly my favorite little thing about Unix based operating systems. I’ve clicked on Macworld’s tutorial page on symbolic links probably 200 times now, because I can never remember its very simple syntax1.
A symbolic link is essentially a shortcut to a directory, much like shortcuts on a Windows desktop to applications. The difference is that for most intents and purposes2, a symbolic link is indistinguishable from actually placing the directory itself in the location of the symbolic link.
Why is this useful? For my current set-up, I have two hard drives: one 80 Gigabyte SSD (named Lappy) and one 500 Gigabyte hard drive (named Lappy Slow). 80 Gigabytes isn’t enough to hold all of my documents, so my ~/Documents folder is actually a symbolic link to /Volumes/Lappy Slow/Documents, which allows for seamless access of the other drive from my main home directory on my SSD.
Symbolic links are also incredibly useful for Dropbox, which I love and use constantly. One of the biggest complaints about Dropbox is that it only backs up what is in your Dropbox directory. But it honors symbolic links! So inside my ~/Dropbox directory I have symbolic links to the school documents folder that I want to backup as well as the folder holding this website. All of this can be done with a simple one line command.
Now the School folder stored in my Documents is also going to be automatically backed up by Dropbox. This is great for folders that you’re too lazy or are unable to move but would still like to be in Dropbox.