The full MacOS installer is required to create a bootable MacOS install disk.

Summary

  1. softwareupdate --list-full-installers - list available versions
  2. softwareupdate --fetch-full-installer --full-installer-version 15.3 - download specific version, e.g. 15.3

Procedure

Download MacOS

List available MacOS versions

$ softwareupdate --list-full-installers

Finding available software
Software Update found the following full installers:
* Title: macOS Sequoia, Version: 15.3.1, Size: 14891477KiB, Build: 24D70, Deferred: NO
* Title: macOS Sequoia, Version: 15.3, Size: 14889290KiB, Build: 24D60, Deferred: NO
* Title: macOS Sequoia, Version: 15.2, Size: 14921025KiB, Build: 24C101, Deferred: NO
* Title: macOS Sequoia, Version: 15.1.1, Size: 14212458KiB, Build: 24B91, Deferred: NO
* Title: macOS Sequoia, Version: 15.1, Size: 14209591KiB, Build: 24B83, Deferred: NO
* Title: macOS Sonoma, Version: 14.7.4, Size: 13332546KiB, Build: 23H420, Deferred: NO
* Title: macOS Sonoma, Version: 14.7.3, Size: 13334287KiB, Build: 23H417, Deferred: NO
* Title: macOS Sonoma, Version: 14.7.2, Size: 13333067KiB, Build: 23H311, Deferred: NO
* Title: macOS Sonoma, Version: 14.7.1, Size: 13339062KiB, Build: 23H222, Deferred: NO
* Title: macOS Ventura, Version: 13.7.4, Size: 11915317KiB, Build: 22H420, Deferred: NO
* Title: macOS Ventura, Version: 13.7.3, Size: 11915737KiB, Build: 22H417, Deferred: NO
* Title: macOS Ventura, Version: 13.7.2, Size: 11916651KiB, Build: 22H313, Deferred: NO
* Title: macOS Ventura, Version: 13.7.1, Size: 11923883KiB, Build: 22H221, Deferred: NO
* Title: macOS Monterey, Version: 12.7.4, Size: 12117810KiB, Build: 21H1123, Deferred: NO

Download MacOS Sequoia v15.3 disk image:

softwareupdate --fetch-full-installer --full-installer-version 15.3

Troubleshooting

PKDownload Error Code=8

If download fails with following error

$ softwareupdate –fetch-full-installer –full-installer-version 15.3 Scanning for 15.3 isntaller Install failed with error: Installation failed Error Domain=PKDownloadError Code=8 “null” … “A server with the specified hostname could not be found.”

it is likely that internet connection cut out midway through the download. Switch to ethernet or mobile hotspot, which may have a more sustained connection than wifi.

And added OpenDNS nameservers.

Settings > Network > selected Ethernet connection > clicked Details > DNS > selected + > added 208.67.222.222 and 208.67.220.220

And restarted download.

References