What is newsyslog?

newsyslog is a behind-the-scenes tool that stops your Mac's log files from filling up your disk.

What is newsyslog?

newsyslog is a log rotation tool. It manages system log files by compressing old logs, deleting very old ones, and making new log files when the current ones get too large. Without log rotation, log files would grow forever and in time eat all your disk space.

How does it work?

newsyslog runs on a schedule and checks log files against rules set in /etc/newsyslog.conf and files in /etc/newsyslog.d/. These rules say:

• How large a log file can get before it is rotated
• How many old copies to keep
• Whether to compress old log files
• How often to rotate regardless of size

Is it the same as the unified log?

macOS has largely moved to the unified logging system (log command), which handles its own storage management. newsyslog still manages old-style log files that some processes and third-party software write to /var/log/.

Does it use resources?

Barely any. It runs briefly on a schedule, does its work, and exits. You will rarely notice it.

Should you worry?

No. It is a standard Unix tool that has been managing logs for decades. It does you a favour by stopping old log files from wasting disk space.

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