Redirect macOS software update download to external volume

[iheitlager]

Problem

Internal disk (228GB) critically low on space. macOS software update downloads consume GBs and cannot complete due to insufficient space — catch-22.

Solution

Redirect software update download cache to /Volumes/Data (1TB external, 899GB free).

Steps

1. Clear stalled download:

sudo softwareupdate --clear-catalog

2. Redirect downloads to external volume:

sudo defaults write /Library/Preferences/com.apple.SoftwareUpdate SoftwareUpdateDownloadDir /Volumes/Data/_swupdate
mkdir -p /Volumes/Data/_swupdate

3. Run the update from System Settings

4. Revert after update completes:

sudo defaults delete /Library/Preferences/com.apple.SoftwareUpdate SoftwareUpdateDownloadDir
rm -rf /Volumes/Data/_swupdate

Also consider

• Delete APFS OS update snapshots to reclaim ~10-15GB
• Restore offloaded apps from /Volumes/Data/_temp_offload via restore-apps.sh

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🤖 Analysis by Claude