Macs have had built-in file sharing since System Software 2, back in 1987. With a few clicks, you can make one or more folders—or even your entire disk—available to other Macs or PCs on your local network. Another computer (your own or someone else’s) can easily connect to your shared folder or volume, see and open the files inside, and—if you’ve granted the necessary permissions—make changes to those files.
Although Apple has made some changes to the “plumbing” of OS X file sharing in recent years, it still looks and acts pretty much the same, at least from the perspective of other Macs ① (Windows PCs have an easier time connecting than they once did).
① Turn on File Sharing in the Sharing pane of System Preferences to allow other Macs and PCs on the local network to access shared folders on your Mac.
Depending on how you set up OS X file sharing, what you get is either true two-way sharing or one-way broadcasting. I use file sharing constantly to access files on other Macs of my own, and it’s also useful in a home or small-office environment where several people need ongoing access to a subset of each other’s files.
OS X file sharing is great for what it does, but it’s not ideal in every situation. Accessing your own shared Mac from a remote network is hit-and-miss, even with iCloud’s Back to My Mac feature, which is supposed to make it almost foolproof. It’s even worse for other users on remote networks—getting that to function may require lots of fiddling with routers, DNS services, and other networking esoterica. And, mobile devices generally won’t be able to see your shared files, even if they’re on the same Wi-Fi network as your Mac. In all those cases, you’ll have better results if you Sync Files and Folders across Devices or Sync Folders with Others.
Enable File Sharing
Open System Preferences > Sharing.
Select the File Sharing checkbox in the list on the left, as shown in the figure above.
The window shows the addresses at which other computers can connect to your Mac. Your Mac should also appear in the Finder sidebar of other Macs on your local network, under Shared.
By default, you can access everything on your drive when you connect from another Mac with your login username and password. To give others access to your data, you must first add the folders you want to share and give each user the desired level of access permission.
Add Shared Folders
Click the plus button under Shared Folders.
Navigate to the folder you want to share, select it, and click Add. Repeat as needed.
Add a User
Select a shared folder ②.
② Add shared folders and specify user permissions in this portion of the window. You can also change user permissions using the pop-up menu next to the user’s name, or click the minus button to delete a user.
Click the plus button under Users.
Select a user from Users & Groups or Contacts.
Click Select.
For new user accounts, enter and confirm a password, and click Create Account. When prompted, enter your login password and click Modify Configuration. Then select Users & Groups, select the new user, and click Select.
button under Shared Folders.