[JazzCatDRP]

My wife's parents have a Mac with an account set up for each of them. There are some files that they both want to be able to access. I showed them the Shared folder, and they started using that. The trouble is, they both have read permissions to any files, but the only one that has write permissions is whoever created the file. Is there any way to change it so any files put in the Shared folder have R&W access for all? Thanks for any tips!

[P]

Good question. The answer is "not really". There is a way to change the write permissions of ALL files made by a certain user to make them writable by all or by a certain group. You might then rely on the permissions of the various folders you set up to control access (remove the execution bit for group and world on all folders you don't want anyone else to touch).

It's not as terrible as it may seem, however. You can add anyone else's write permissions on any file you own, and on any file you don't own, you can make a copy (which you will then own), add the other person's write permissions and delete the original.

[JazzCatDRP]

Originally Posted by P 

There is a way to change the write permissions of ALL files made by a certain user to make them writable by all or by a certain group. You might then rely on the permissions of the various folders you set up to control access (remove the execution bit for group and world on all folders you don't want anyone else to touch)..

That's interesting...could you explain that?

[P]

You have to reset the user mask, and I hoped you wouldn't ask how because I'm not sure what the best way is to do it anymore. You used to be able to do it in Netinfo, but Netinfo is gone.

Before you read any further, backup. This is tricky business, and you can hose your system if you mess up. You have been warned.

It seems like this is the way to do it cleanly. The umask you want is either "002", which means that all files are writable by everyone in the group, or "000" which means that all files created are writable by anyone. If you're on Leopard, the method you want is the first one list in the linked document, so create a file called "launchd-user.conf" in the /etc folder, make its contents "umask 002", save as a plaintext file and reboot.

Unfortunately, the default group for all files created includes only the user itself, so either you

* change that to "umask 000", making all files created writable by all. Not a good idea if you have anyone else that uses the machine regularly and shouldn't have access, or for that matter if you have daemons or servers running on the machine.
* change the default group of one of your parents to that of the other. You do this by going to the accounts pane, unlocking with the padlock and selecting "Advanced settings" from the control-click menu for one user. In that pane, you can change the default group ID. It's a number like 501, 502, or something like that - make sure those numbers are the same, and everything should work for newly created files. Existing files need to be changed manually - easiest is to do it from the Finder's Get Info box.