If you use a Mac and have ever had to copy Lightroom or Aperture catalog files or anything in the Application Support folder from one computer to another or even from one user to another there’s a good chance you’ve run into permissions issues.
You can use Finder’s Get Info function, but that becomes tedious very quickly you have to apply it to multiple files and folders. It also doesn’t help with Group assignment issues.
Of course, you have much more power and flexibility using the command line in Terminal, but not everyone’s comfortable using the command line, and unless you do it regularly it can be hard to remember precisely what syntax to use.
PropEdit is a free application that combines the power of the command line and the simplicity of a user interface.
I use it most often to set Owner permissions, but you can also set Group and World settings as well as individual flags on files or folders.
And choosing whether to set the permissions for a file or all files enclosed in a folder is as simple as hitting “apply” or “apply to enclosed items.” And one of the things I like is that in the time it would take me to Google the command line syntax I need I can use PropEdit and have it done along with a very simple, visual way to confirm that the correct permissions have indeed been applied to the files I want them applied to.