John's macOS / Mac OS X tips

 Apple mail searches using "Envelope Index" database files. These are located in  ~/Library/Mail/V#/MailData where # is some number. 1. Quit mail 2. In the Terminal, just type: find ~/Library/Mail/V?/MailData -name "Envelope Index*" -delete 3. Re-open mail. It should re-index.

 These days when you download the 10.13 installer ( https://apps.apple.com/us/app/macos-high-sierra/id1246284741?mt=12 ) it complains that the installer is corrupted or broken and won't install. Really what has happened is Apple doesn't sign the installer anymore and so the certificate is invalid. However, certificates are date-sensitive. So, simply unplug your target machine from internet so that it doesn't automatically talk to Apple or reset its date/time, and set the time manually like so. Make sure the installer has quit first. 1. Open Terminal 2. Type:     date -s  0711141518 or any other date in 2018 or earlier.  3. Open the installer again. You should now be able to install 10.13.

Mac OS X used to have a sharing function which turned apache (webserver) on so you could make websites on your machine. However, they turned that off, for whatever unknown reason. To enable apache now, do the following. First, let's find out your username. Open /Applications/Utilities/Terminal.app It will come up with a terminal screen Type: whoami The machine will answer with your login name. Note what it is. Let's say it's " bob " for now. Now type: sudo vi /etc/apache2/httpd.conf This will start you off editing the apache webserver configuration file ( https://www.youtube.com/watch?v=dFUlAQZB9Ng ). Yes, this is a unix machine. The way you edit it is not by mousing, contrary to what we see in Jurassic Park(tm), but by typing in and editing text files. To search for the necessary lines, type a forward-slash (/) Type what you want to search for, in this case, php . Press enter after typing php as the search. You will find a line like this: #LoadModule php7_modul...