Access Control Lists (commonly known as ACLs) are a way of specifying complicated permissions to objects.

Those of you from the UNIX world may remember when you have been in a situation like the following:

Techies need read/write to a directory. Marketing needs read. Joe needs full access.

This is an impossible scenario with classic owner/group/others permissions. You can't have two groups that need two different permissions. With ACLs you can!

Requirements

The basics for using ACLs on ext2/3 partitions is:

• Having a patched kernel to allow it
• Having the ACL utilities
• Having a slightly modified version of fileutils.

It is also important to have a recent version of e2fsck otherwise it'll screw up your ACLs.

Kernel bits

Now! With the patched kernel, the appropriate options are (in menuconfig): File systems->POSIX Access Control Lists File systems->Ext3 journalling file system support File systems->Ext3 journalling file system support->Ext3 extended attributes File systems->Ext3 journalling file system support->Ext3 extended attributes->Ext3 POSIX Access Control Lists

If you use ext2, do the same for `Second extended fs support' a bit lower down.