Show Filename Extensions in Mac OS X
File extensions (.jpg, .txt, .pdf, etc) are hidden by default in Mac OS X, this makes for a cleaner user experience and is fine for most users, but it drives me nuts and it’s one of the first things I change when setting up a Mac. You can either set all extensions to be displayed through a universal setting, or you can set extensions to be shown on a per file basis with the help of the Get Info command, here’s how to do both:
Show or Hide All File Extensions
- From the Mac OS X Desktop, pull down the “Finder” menu and choose “Finder Preferences”
- Click on the “Advanced” tab (gear icon)
- Check the box next to “Show all filename extensions”
Changes are immediate and you’ll find the extensions visible instantly across the Finder:
Selectively Show or Hide Filename Extensions
If you’d rather not see them all, or if you want to hide some and show others, you can also show (or hide) file extensions on a per file basis.
- Select a file and hit Command+i to bring up the “Get Info” window
- Click the arrow alongside “Name & Extension:” to expand the options, and check or uncheck “Hide extension”
For many users, not seeing filename extensions is probably fine, but I often set custom file associations, and knowing the extension will let you know what app is going to open with each file without looking at the “Open With” menu to be certain.