If you hang around XDA long enough, you’ll eventually encounter a modification that requires you to change file permissions. Typically, it’s a system APK or file that needs to be dropped somewhere that only root users can get to. By setting the proper permissions, the file can be used by the system correctly. If you don’t set permissions properly, it can make whatever mod you’re trying to use not work. This is nothing new, as Linux and Unix users have been dealing with file permissions for a very long time.
Since permissions are everywhere and we mess with them a lot, all new Android users would do best to understand them. This is the mindset that XDA Senior Member Sun90 had while writing up a tutorial that describes file permissions on Android, what they do, and how to use them. It is based on an older tutorial dealing with permissions in Unix.
In essence, Sun90 runs users through the very basics of file permissions. He includes relevant examples of times when users will have to deal with file permissions, how to set file permissions using a root manager, and what the commands actually mean. There is a lot of information aimed at helping new users packed in, and if you read the older tutorial, there’s a whole bunch more.
To learn more, head over to the original thread._________