Apple Mac OS X Server manual Setting Permissions, Viewing Permissions

Setting Permissions

To control access to your information, Mac OS X automatically sets permissions for disks, folders, and files. You can only change permissions to items that you own.

Be sure that the default permissions are appropriate. For most purposes, files should be accessible to the other members of your group. If you have private or confidential information, the default permissions of the files may allow others to see it. To prevent others from accessing personal information, create a folder and set its permissions to “owner.” Then place your confidential files into it. No other users will be allowed into the folder.

Mac OS X provides distinct permissions for three types of users:

ÂThe “owner” of the item, who is usually the person who created the item

ÂAny member of the group assigned to the item by Mac OS X

ÂAny other user with access to the computer

There are four levels of permission:

ÂRead & Write allows a user to open the item to see its contents and change it.

ÂRead Only allows a user to open the item to see its contents, but not change or copy the contents.

ÂWrite Only makes a folder into a drop box. Users can copy items to the drop box, but cannot open the drop box to see its contents. Only the owner of the drop box can open it to access items.

ÂNo Access blocks all access to the item so that users can’t open the item, change its contents, or copy its contents.

Viewing Permissions

Each security group is assigned a code that controls that group’s permissions:

Âr (read) allows the user to see the item but not make changes.

Âw (write) allows the user to see and make changes to the item.

Âx (execute) allows the user to run scripts or programs.

Â- (access) means access is turned off.

To view permissions for files and folders, enter the ls -lcommand. For each file or folder listed, you see the permissions, owner and group name, and file or folder name.

Some examples of permission settings:

ÂThe following file (-) displays read, write, and executable permissions for owner (rwx), group (rwx) and all others (rwx):

-rwxrwxrwx

ÂThe following file (-) displays read, write, and executable permissions for owner (rwx), and group (rwx), but no permissions for others (---):

-rwxrwx---

Chapter 8 Working with Users and Groups

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