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Take Control of Permissions in Leopard
Solve quirky problems, increase privacy, and share files better by managing permissions in Leopard.
Permissions problems got you down? Turn to Unix expert Brian Tanaka's unique guide to the permissions in Mac OS X 10.5 Leopard that control access to your files, folders, and disks. You'll learn how to keep files private, when to set Ignore Permissions, what happens when you repair permissions, how to delete stuck files, and the best ways to solve permissions-related problems. Advanced concepts include the sticky bit, Leopard's more-important access control lists, bit masks, and symbolic versus absolute ways to set permissions. The book covers how to take control of permissions via the Finder, with Mac utilities, and using the command line.
Snow Leopard? See the blog tab below for information about update plans.
More Info
Contents & Intro
FAQ
Blog
Read this ebook to learn the answers to questions like:
Why do so many problem-solving sites suggest that I repair permissions?
Why can anyone with an external drive access my account?
Why can't I always access my own files when I boot from an external drive?
What should I do if someone tells me to "set the permissions to -rw-r--r--"?
What are promiscuous permissions, and should I be informing the vice squad?
What are access control lists (ACLs), and what's new about them in Leopard?
How do I use the Unix command line to control permissions?
What Mac utilities can change permissions, if I don't want to learn Unix?
How do I set up and manipulate account groups from System Preferences?
Now that the NetInfo database is gone in Leopard, how do I edit account settings such as numeric UID?
Book Info
86 pages
Version 1.1
Updated 06-Oct-08
1.7 MB download
ISBN: 193367136X
Free sample with Table of Contents, Introduction, Quick Start, and section starts.
About the Author
Brian Tanaka has worked for a variety of companies including the Well, SGI, Intuit, Nintendo, and RealNetworks. Today, his own company, Martingale-Oak LLC, provides Unix and open source technologies consulting. His articles have appeared in Linux Journal and Sysadmin Magazine.
This book helps you control the often-perplexing world of permissions in Mac OS X 10.5 Leopard. It explains how permissions work, how to resolve common problems, and how to best control access to your files in a variety of situations. Although this book has a different title, it is effectively the second edition of Take Control of Permissions in Mac OS X. This book was written by Brian Tanaka, edited by Tonya Engst (with help from Sandro Menzel), and published by TidBITS Publishing Inc.
Introduction
Even if you don't know a thing about permissions, if you're using Mac OS X 10.5 Leopard, you're using them right now. Every file and folder on your computer carries permissions from the moment it's created until the moment it's deleted. Because permissions are literally everywhere on your computer and because they control who can access what, it's tremendously advantageous to understand them. You'll have better control over your Mac, and you'll be able to share items and access shared items with greater ease.
Problems arising from improperly set permissions are common and can be frustrating: Sharing files among users on one computer can be problematic if you don't understand permissions, and sharing items on a network raises yet another set of potential problems.
In this book I teach you how to prevent and fix permissions problems with ease and much more. You'll learn how to interpret and manipulate permissions with the Info window in the Finder, Disk Utility, third-party tools, and Unix commands. You'll learn about accounts and groups, and how permissions control them; how default permissions work; how to repair permissions; and how to ignore permissions on an attached volume.
Equipped with this expertise, you'll be able to handle permissions problems when sharing files locally or across networks, booting from multiple volumes, exchanging files with other users, running FTP and Web servers, and much more.
Quick Start
The first sections of this book teach the basics of permissions and how to set them. The remaining sections explore more advanced techniques and concepts that help you solve problems.
Learn about permissions:
Find out what permissions are, and why you need them. See About Permissions.
Permissions are composed of simple interrelated parts. Discover how they work together. See The Anatomy of Permissions.
If you already know a bit about permissions and want an overview of what's new in Leopard, read What's New.
Set permissions:
There's more than one way to set permissions. See Choose a Method of Setting Permissions.
Learn to Set Permissions Using the Info Window and to Set Permissions Using Third-Party Tools. And, if you need more fine-grained tools for controlling permissions, read Use Access Control Lists.
To solve a permissions-related problem, see Problems and Solutions (next page), for a quick index to helpful info.
If you enjoy working in Unix or need the fine-grained control that Unix can provide, Learn Advanced Unix Techniques.
Delve deeper into permissions:
Discover how your Mac assigns default permissions in Understand Default Permissions, and increase your permissions IQ by reading Work with User Names, UIDs, and GIDs.
Learn to use two important Mac OS X features in Understand Ignore Ownership, and Repair Permissions with Disk Utility.
Unix commands empower you to do things you can't do from the graphical user interface, which you'll see when you Learn Advanced Unix Techniques.
Problems and Solutions
I discuss a variety of common problems in Appendix A: Fixes For Common Problems, but you will find help with solving other problems throughout the book. Use the links below to navigate to info that will help you with specific problems:
I'm having trouble with The Shared Folder.
The Info window doesn't show permissions settings I know exist. See Set Permissions Using Third-Party Tools and Learn Advanced Unix Techniques.
I don't own my own files! See Work with User Names, UIDs, and GIDs.
I am concerned about the privacy of files and folders that I created and saved in my user account, and I want to make sure that others on the computer cannot access them in any way. Read The Case of the Promiscuous Folder.
When do I use Ignore Ownership on This Volume? See Understand Ignore Ownership.
Everyone tells me to use Repair Permissions but I don't understand what it does. Learn the real story in Repair Permissions with Disk Utility.
I can see why understanding octal is useful when setting permissions, but I can't seem to get my head around it. See Appendix B: Converting To Octal.
When I copy or create items, I can't predict what the permissions will be. It's driving me batty! Find help in Understand Default Permissions.
Q: Do you have an ebook that covers permissions in older versions of Mac OS X?
Q: I have the older Take Control of Permissions in Mac OS X. Is there a discount if I upgrade to this ebook?
A: Yes, there is a 75% discount. Click the Check for Updates button in your copy of the book to access the discount.
Q: Do you explain the correct permissions for the WebServer/Documents folders?
Brian's answer: The ebook explains permissions so thoroughly that I feel confident you'll have no problem at all setting and maintaining the permissions on the Webserver/Documents folders (and all the other folders on your Mac). That said, if you have specific questions that aren't covered by the ebook, I'd be glad to help to the degree I'm able.
Ask a Question
Feel free to ask us if you have a question about this book!
Send Us Your Comments!
How could we not publish such kind words? If you'd like to send us your comments (good or bad, though we hope they're all good), just click the Feedback link on the cover of your copy of the ebook. Be sure to let us know if we can publish your comment. Thanks!
Update Plans
January 2010 -- Brian is working on a Mac OS X 10.6 Snow Leopard edition of this book. We plan to release it in 2010, sometime after Macworld Expo in February, but we don't yet have a good prediction for exactly when. Here is a summary of changes in Snow Leopard that Brian is currently investigating:
ACLs are on by default in Snow Leopard. Therefore, we no longer
need to test whether or not ACLs are on. Further, we previously
used fsacltl() to test ACL status, but fsacltl() has been removed
from Mac OS X.
In the last edition, a umask in /etc/launchd.conf did not work,
contrary to Apple's documentation. In Snow Leopard, it does work,
but the warning to avoid using this technique still stands.
Perhaps the biggest issue is that a umask in $HOME/.launchd.conf
does not work, contrary to Apple's documentation. That means that
I know of no way in Snow Leopard to set default permissions on files
and folders created by the Finder and Mac OS X applications on an
account-by-account basis. This issue affects the security policies
of any multi-account Mac OS X computer. Several sections of the
book will change significantly due to these new developments.
Many of the default permissions (and ACLs) that result from the
copy operations in the "Permissions on Copied Items" section have
changed. I will update the tables accordingly. For example, when
copying a file to another user's Drop Box, unlike in versions prior
to Snow Leopard, the ACLs on the resulting file are such that the
receiving user can edit the file, and more interestingly, after
saving, the file ownership switches to the receiving user's account.
Finally, there are a number of small changes. For example,
the output of the id() command has changed, and the system account
that owns the Apache processes was www but is now _www.
Anyone who purchased the PDF of the Leopard edition from the Take Control Web site during August 2009 or later will receive a free update to the Snow Leopard edition, once it is available.
This ebook discusses three third-party tools: FileXaminer, Super Get Info, and XRay/XRay II. Today, only FileXaminer remains. Super Get Info has been discontinued. XRay has Leopard and Snow Leopard issues the author is not intending to address. The sole survivor, FileXaminer, now has a 14-day trial. (The previous trial period was 7 days.)
