How to reinstall MacOS with external bootable disk installer for Mac operating system. macOS Catalina, macOS Mojave, or macOS High Sierra. You can use an external drive or secondary volume as a startup disk from which to install the Mac operating system.
This article was inspired after I helped a friend recover their Mac operating system and documents. Having an external drive with macOS really help and did a quick install.
After installing from an offline version, do run the Apple software update to get the latest updates and version. You can also run from the command line
sudo softwareupdate -ai.
The purporse of this post is to share the links from support.apple.com for the instalations of the various Mac operating system versions.
How to create a bootable installer for macOS
How to upgrade to macOS Catalina
How to upgrade to macOS High Sierra
How to upgrade to macOS Mojave
How to upgrade to OS X El Capitan
How to reinstall macOS from macOS Recovery
Always have a backup of your data. Use at your own responsability and happy learnings,