## Getting the installer
See [here](https://support.apple.com/en-gb/HT211683). There are links that go via the App Store to Update, and Update downloads the installer. Once downloaded, **do not run it normally** but see below. Additionally, you may wish to copy the installer to an external drive.

For example, the Catalina url is
```plaintext
macappstores://apps.apple.com/app/macos-catalina/id1466841314?mt=12
```
and note that you can't find these via the search facility of the App Store.

For reference, the [URLs]() are:
```plaintext
macappstores://apps.apple.com/app/macos-ventura/id1638787999?mt=12
macappstores://apps.apple.com/app/macos-monterey/id1576738294?mt=12
macappstores://apps.apple.com/app/macos-big-sur/id1526878132?mt=12
macappstores://apps.apple.com/app/macos-catalina/id1466841314?mt=12
macappstores://apps.apple.com/app/macos-mojave/id1398502828?mt=12
macappstores://apps.apple.com/app/macos-high-sierra/id1246284741?mt=12
```
and the `.dmg` [URLs]() are:
```plaintext
http://updates-http.cdn-apple.com/2019/cert/061-39476-20191023-48f365f4-0015-4c41-9f44-39d3d2aca067/InstallOS.dmg # Sierra
http://updates-http.cdn-apple.com/2019/cert/061-41424-20191024-218af9ec-cf50-4516-9011-228c78eda3d2/InstallMacOSX.dmg # El Capital
http://updates-http.cdn-apple.com/2019/cert/061-41343-20191023-02465f92-3ab5-4c92-bfe2-b725447a070d/InstallMacOSX.dmg # Yosemite
https://updates.cdn-apple.com/2021/macos/031-0627-20210614-90D11F33-1A65-42DD-BBEA-E1D9F43A6B3F/InstallMacOSX.dmg # Mountain Lion
https://updates.cdn-apple.com/2021/macos/041-7683-20210614-E610947E-C7CE-46EB-8860-D26D71F0D3EA/InstallMacOSX.dmg # Lion
```
at time of writing this (2023-03-16).
## Making the media
Summarised from [here](https://support.apple.com/en-gb/HT201372). Use the appropriate line from
```bash
sudo /Applications/Install\ macOS\ Ventura.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
sudo /Applications/Install\ macOS\ Monterey.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app
```
note: If your Mac is using macOS Sierra or earlier, the command should conclude with `--applicationpath` followed by the appropriate installer path, as shown in the command below for El Capitan.