Watch Live System Logs with log stream

Tail macOS's unified log in real time, filtered with predicates so you only see the messages you care about.

macOSlogdebuggingmonitoringLow risk

Run `log stream --predicate 'process == "<name>"' --level debug` to follow live messages from one process.

01Command

Command

$ log stream --predicate 'process == "WiFiAgent" AND messageType >= 16' --level debug

02What it does

log stream prints events as they arrive, unlike log show which replays the archived store. The --predicate syntax matches process, sender, eventMessage, category, or messageType, so you can watch one daemon's debug chatter without noise. Press Ctrl+C to stop, and add `--style compact` for denser output when tailing over SSH.

03Risk

RiskLow risk

RequirementsmacOS 10.12 Sierra or later.

!Warning: Debug-level streams from busy processes generate enormous output — always narrow the predicate first.

04Undo

✓No undo needed — this command does not change persistent state.

05Sources

LOG Command: Access log messages in macOS
SS64 · technical · 2026-09-17
Evidence: Documents log stream with --predicate, --level, and --style options for live unified-logging output.

Last verified: 2026-09-17 · Category: System & Settings

06Related solutions

Search the Unified Log with log show

macOSlogtroubleshootinglogging

Filter macOS's single unified log by process, message type, or subsystem straight from the Terminal.

Low risk ✓ 2026-09-17