How to Change File Permission From Read-Only to Read-Write on a Mac
By David Weedmark
Updated August 23, 2018
As long as you have administrative access to your Mac computer, you can change the permissions for a file, folder or disk on the Mac from "Read Only" to "Read & Write." This is important to know if you want a coworker to collaborate on one of your files or if you need to modify a file someone sent to you that came as "Read Only." If the file is on someone else's computer or on a shared drive, you can't change the permissions unless you created the file or have administrative access to that drive.
Launch a new Finder window. You can do this quickly by clicking the blue "Finder" icon in the dock at the bottom of the screen. Click a disk, folder or file to highlight it.
Hold down the "Command" key and press "I" to open the Get Info window for the highlighted item.
Scroll down to "Sharing & Permissions" in the Get Info window. If you can't see a list of permissions below this section title, click the "Disclosure Triangle" beside the title to see the sharing and permissions.
Click the "Lock" icon in the window's bottom right corner if the lock is closed. Enter your password as prompted. The lock icon changes to the unlocked position, indicating that you can now make changes to the permissions.
Choose a user or group of users in the list, and click the "Read-Only" privilege beside it. Select "Read-Write" from the drop-down menu.
Click the "Lock" icon when you have finished changing permissions to prevent anyone from changing them again without the administrative password.
Information in this article applies to Mac OS X Mountain Lion. It may vary slightly or significantly with other versions or products.
A published author and professional speaker, David Weedmark has advised businesses and governments on technology, media and marketing for more than 20 years. He has taught computer science at Algonquin College, has started three successful businesses, and has written hundreds of articles for newspapers and magazines throughout Canada and the United States.