MacOS – Is it possible to use etc/hosts to block a specific part of a whole website

Nothing will break (or hasn't for me whenever I resort to this on occasion) - you'll have to remember to re-do the permissions if and when the OS updates that file systematically. You'll also want to watch the permissions if you ever "repair permissions" since that file is likely recorded in a system receipt. I'd go so far as to set a launchd task to daily enforce your "custom" permissions if you feel it's worth that much work and log something to the console about the need for this "adjustment"

This is a far faster and simpler (and therefore probably better) solution to setting up your own DNS or NIS even though a trip down memory lane would be fun for a few moments:

• cd /var/yp
• make

This specific request "I want to block sites and need to edit /private/etc/hosts" requires you to know how to edit a normally hidden system configuration file. Your information on an older processor and OS are excellent, but in this case all OS X work the same for modifying the unix host file.

This error is intentional and by design, since making this file easy to modify means that you could easily break the computer from working (and also this file is very desirable for malware or trojan/virus software to attack - imagine if your banking website was directed to another site to harvest your user and password before sending that information to your real bank as part of a "man in the middle" attack.)

Most people use a terminal based editor since it's easily to use the sudo command to temporarily edit the file with root permissions - taking care not to undo the protections that make this not writable by any users directly.

• Mac OS X Server: How to edit configuration files

As always, be sure you know how to correct a change like this - the normal Time Machine backup should preserve this file if you know how to to navigate to the /private/etc folder using Finder Go -> Go to Folder... keyboard shortcut before entering Time Machine.