Change user rights ONLY with terminal

Question

Hi!
I've got some problems with adding users on a specific folder using the "information" window. It is the iPhoto Library folder. I give 2 users "RW" permissions on the folder, but only one is able to see the iPhoto Library. Just so you know : I did it on my computer, and it worked.
Here's what I'd like to do, and ONLY WITH THE TERMINAL :
1°) delete all users access except for one account ("GG" for instance) on the "iPhoto Library" and all its containing files and folders
2°) give the 2 accounts all rights on the folder and all its containing files and folders.
For the second part, I found this :
sudo chmod +a "UserName allow delete,chown,list,search,add_file,\
addsubdirectory,delete_child,file_inherit,directoryinherit" \
/Users/Shared/iPhoto\ Library
Does it work well?
Thanks.

Answer 1

Hello,
All what I read in this thread is bizarre (no offense here).
a/ If you want to block access to files within a folder to a specific Unix user, you don't have to recursively alter the permissions of all files within the folder. Just block the "execution" permission of the top folder and noone will be able to look into it. It's a 0740 permission
drwxr-----
Currently, iPhoto Library folder is 0755 (drwxr-xr-x)
b/ What is your "requirement" first? You're talking us about a problem you have with your "proposed solution", but at first, we're not sure this is the best solution to address our problem !!!
What I understand is that you want to restrict access of someone to some iPhoto Library. Well ! That doesn't tell us much of the background situation.
You're telling us you want to add 2 users the permission to view this iPhoto Library folder.
Well, tell us first:
- Where is located that iPhoto Library folder
- How many users exists on your system already
- Why 2 users and not 3. This specific requirement requires more details given to us.
Globally, the Unix permission scheme considers Owner, Group and Others. Not one specific user. To create a permission mask for a specific user, you have to use ACLs (Access Control Lists), recently added to MacOSX.
As you want to use shell commands (aka Terminal, as you write), please check the "man pages" for chmod.
Now, if you want to share your photos with someone else - even on the same computer. You can simply turn "Sharing" on in your iPhoto Preferences; Use Fst User Switching to allow two or more users to have an opened session; and leave your account session on with iPhoto iconized. All users on your machine will be able to access your photos ... without messing up with file permissions schemes.
Tell us more then on what is your initial goal.
Rgds,
Thierry