Because Mac OS X is built on a UNIX core, you can set permissions by entering UNIX commands in Terminal.
Each file or directory has three types of security groups:
Owner: The owner or creator of the file or directory.
Group: The group to which the file or directory is assigned.
All Others: Anyone who isn’t the owner or isn’t assigned to the group associated with the file or directory.
Each security group is assigned a code that controls that group’s permissions:
r (read) allows the user to see the item but not make changes.
w (write) allows the user to see and make changes to the item.
x (execute) allows the user to run scripts or programs.
- (access) means access is turned off.
To view permissions for files and directories in Terminal, type the “ls -l” command. For each file or directory listed, you see the permissions, owner and group name, and file or directory name.
In the following example of permissions, the file (-) displays read, write, and executable permissions for owner (rwx), group (rwx), and all others (rwx):
-rwxrwxrwx
In the following example of permissions, the file (-) displays read, write, and executable permissions for owner (rwx) and group (rwx), but no permissions for others (---):
-rwxrwx---
In the following example of permissions, the file (-) displays read, write, and executable permissions for owner (rwx), but no permissions for group (---) or others (---):
-rwx------
In the following example of permissions, the file (-) displays read and write, but no executable permissions for owner (rw-), group (rw-), and others (rw-):
-rw-rw-rw-
In the following example of permissions, the file (-) displays read, write, and executable permissions for owner (rwx), but only read and executable permissions for group (r-x) and others (r-x):
-rwxr-xr-x
In the following example of permissions, the file (-) displays read, write, and executable permissions for owner (rwx), but only read permissions for group (r--) and others (r--):
-rwxr--r--
For more information on permissions in UNIX, see the man page by entering the “man ls” command in the Terminal window.