What is logd?

logd is one of the most basic processes on modern macOS. It runs all the time in the background.

What is logd?

logd is the unified logging daemon, introduced with macOS Sierra. It replaced the older syslogd and ASL (Apple System Log) systems with a single, fast logging system. Every process on your Mac, from the kernel to apps, sends its log messages through logd.

What does it do?

• Receives log messages from every process on the system
• Sorts messages by subsystem, category, and severity level
• Stores logs in a compressed, binary format
• Manages log storage, keeping recent logs and clearing old ones
• Provides log data to Console.app and the log command-line tool

How do you view logs?

You can view unified logs using:

# Show live log stream
log stream

# Show recent logs
log show --last 5m

# Filter by process
log show --predicate 'process == "Safari"' --last 1h

# Filter by subsystem
log show --predicate 'subsystem == "com.apple.wifi"' --last 10m

Or open Console.app for a graphical view.

What about logd_helper and logd_reporter?

• logd_helper: handles tasks that logd cannot do within its sandbox, such as reaching certain system files
• logd_reporter: processes and sends log-based diagnostic data to Apple (if analytics sharing is turned on)

Does it use a lot of resources?

logd is built for speed and low overhead. It handles thousands of log messages per second with very little CPU use. The compressed binary format keeps storage needs small.

Should you worry?

No. It is a vital macOS process. Without logd, there would be no system logging: no crash reports, no diagnostic data, and no way to track down problems.

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