Where Is the macOS Unified Log Stored?
The macOS unified log lives in /var/db/diagnostics and /var/db/uuidtext, read with the log command, not a text editor.
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Modern macOS funnels nearly all system and app logging into the unified log: a compressed binary store you query instead of read. Two system directories hold the data and the message templates separately.
There is no log file to open. The log command and the Console app are the readers, with predicates filtering the firehose down to one process or fault. Copying the raw directories to another Mac teaches you nothing without the matching tools.
Where macOS stores this, by platform
/var/db/diagnostics
Main log store with persist and special event data. Message text templates live in /var/db/uuidtext. Query with log show --predicate and --last 1h rather than browsing the raw files.
Frequently asked questions
how do i read macos system logs
Use log show with a predicate like --predicate 'process == "Finder"' and --last 1h, or filter in Console.app. The raw files under /var/db are compressed and unreadable directly.
can i delete var db diagnostics to free space
The system purges old entries automatically under storage pressure. Manual deletion risks breaking logging until reboot. Check storage in System Settings first, since the log is rarely the real hog.
where did system.log go on modern macos
Into the unified log. The old text files in /var/log still exist for some services, but most output moved to /var/db/diagnostics and only surfaces through the log tool.
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