How to Modify Permissions with the Info Window
The Info window allows you to modify permissions for users, groups, and everyone else. It doesn’t provide the same level of granular control as the chmod command, which you’ll learn about in the next section, but it’s a good way to quickly limit access to a file or folder.
Here’s how to modify permissions with the Info window:
Click a file or folder to select it.
From the File menu, select Get Info. One of the windows shown below appears.
Click the disclosure triangle next to Sharing & Permissions to display permissions for the selected file or folder.
Click the lock and authenticate with an administrator account.
Use the menus next to users and groups to change the permissions.
When you’re finished, close the Info window.
Changes are effective immediately.
How to Modify Permissions with chmod
For total control over permissions, you can use two Unix commands - ls and chmod - to display permissions and modify them. Assume you want to find a folder’s current permissions and then change them to 755. This would give you as the owner read, write and execute permissions, and everyone else read and execute permissions.
Here’s how to find a folder’s current permissions and change them:
Open the Terminal application.
Type ls –l, and then press Return. The symbolic permissions of the files and folders in your home directory are displayed, as shown below.
Type chmod 755 foldername, and then press Return. This changes the permissions of the folder to rwxr-xr-x.
When it comes to using the ls and chmod commands, practice makes perfect. Try modifying the permissions on a couple of sample files. If you need more help, use the man command to display the manual pages for these commands (e.g., man ls).
Final Thoughts
Permissions as a security control are more effective in some environments than others. Schools and offices have a real need for permissions - there are lots of users, and the information stored on the computers can be valuable. In single-user households, where only one person uses a Mac, convenience might outweigh any perceived security threats. It’s all about finding the right balance for your environment.
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