Published at LXer:

The traditional file permission model, where read, write, and execute permissions are set on each file for the user, group, and others (UGO) has one drawback: It can't be used to define per-user or per-group permissions. For that, you need to employ access control lists (ACL). Eiciel is a graphical tool that integrates with the Nautilus file manager and allows for easy ACL management. The UGO model lets you associate only one group with a file. If you try to define read permissions on a file for user Charlie and read and write permissions for user Alexia, and Charlie and Alexia belong to different groups, you'll see what I mean. With ACLs, you can specify elaborate permissions for multiple users and groups.

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