What is Unix permissions and ACLs
 

Unix permissions are the same.

People say Unix permissions are the same but ACLs implementations vary across Linux distros and OS X / windows.

What does this mean ? And what is ACLs .


I was reading this at one of those yahoo groups talking about OS X Lion that just came out and talking about ACLs .

You can think about ACL like extended old Unix permissions. You can for example give many users or groups different permissions, not only owner, group and others, you can create default permissions, etc. You can found more info in "man 5 acl".

What may some of the permissions be and why does this implementations vary across Linux distros and windows.

Permissions
https://secure.wikimedia.org/wikiped...em_permissions
http://www.hackinglinuxexposed.com/a.../20030417.html
http://www.hackinglinuxexposed.com/a.../20030424.html
http://linux.die.net/man/1/chmod

ACLs
http://www.linuxtopia.org/online_boo...5_ch-acls.html
http://linux.about.com/library/cmd/blcmdl5_acl.htm
http://linux.die.net/man/1/setfacl
http://linux.die.net/man/1/getfacl

I think the confusion here is Linux vs windows .Thing is I really do not know much about any OS other than windows

In windows we have guest accounts ,standard accounts ,administrator accounts and each account as permissions levels .We also have granularity control of each user or group of user of what each user or group of user can or cannot do.

But from my understanding Linux like Unix are not like this.My understanding it is more a on and off you root or you are a user .

Really not. There are a few differences, but like in Windows, you can choose various permissions for different users and groups. It may look that there is only you and root, beacuse for example in Ubuntu you have no guest, admin or normal user groups, you can create it if you need. But there is also some service accounts. I see it is common that every service has its own group and account for separation, not like in Windows, every service is under LocalService or NetworkService accounts with escalated privilages. As I known there is also no "denied" permissions in Linux like in Windows XP, by default it is denied and you can only allow for something.

I don't known which version of Windows you have in mind, as between 98 and ealiers, XP, Vista and newest are major changes. The latest behave similar to Linux with sudo.

About root - by default (without SELinux, etc.) he is not restricted by permissions, it is like account SYSTEM in Windows XP.