Frequently Asked Questions (FAQs)

A list of some frequently asked questions, and links to additional resources.

Why was this site created?

This site was created out of frustration. When dealing with file permissions, I tended to forget how to transpose octal notation to symbolic, and back again. Where as it would be easier to just look up the information I needed. Sometimes I would get lucky with a stackoverflow post, but to my knowledge there was not a consolidated, or solitary place where this information was contained.

However the primary reason was to create a resource for developers to get answers they need quickly, so they can get back to solving problems that matter.

How are there 4608 unique file permissions combinations?

Octal notation can be expressed either 1 of 2 ways, by using 3 or 4 digits respectively; where 4 digits permissions are used exclusively when setting a stickybit, uid, or gid. Octal notation, as the name suggests is made of a numerical system of 8 numbers (0-7).

When using 3 digits Octal notation the total number of combinations is 512, which is calculated by (8 * 8 * 8). Each 8 representing the total number of possible (0-7) values for each of the 3 characters.

When the same calculation is performed for the 4 digits values there are a total of 4096 combinations (8 * 8 * 8 * 8).

The grand total then arrived at is 4608 (512 + 4096).

* Technically there are some duplicates, since there is overlap between the 3 and 4 digits values ex: 777 and 0777 technically equal the same permissional value. However both lists were included in order to create a complete list.

How do I change file permissions?

You have come to the right place, those are the types of questions we're here to answer.

If you're unable to find the answer you're looking for. Here are a few other resources: