Continuous Monitoring with --follow¶

Use --follow to re-parse log files at a regular interval and refresh the report automatically.

Basic usage¶

quellog --follow /var/log/postgresql/*.log

By default, this analyzes the last 24 hours and refreshes every 30 seconds. The terminal output updates in place. Press Ctrl+C to stop.

Custom interval and time window¶

Adjust the refresh interval with --interval and the lookback window with --last:

quellog --follow --interval 1m --last 1h /var/log/postgresql/*.log

This refreshes every minute and only considers the last hour of log entries.

HTML dashboard¶

Combine --follow with --html and -o to produce a self-refreshing HTML dashboard:

quellog --follow --interval 5m --html \
  -o /tmp/quellog-dashboard.html \
  /var/log/postgresql/*.log

Open /tmp/quellog-dashboard.html in a browser. quellog rewrites the file on each refresh cycle — reload the browser to see updates.

JSON output for external tools¶

Feed structured data to monitoring pipelines or alerting systems:

quellog --follow --interval 1m --json \
  -o /tmp/quellog.json \
  /var/log/postgresql/*.log

The JSON file is overwritten on each cycle.

Running in the background¶

Use a systemd service or cron to keep quellog running unattended.

systemd -- create /etc/systemd/system/quellog-monitor.service:

[Unit]
Description=quellog continuous log monitoring
After=postgresql.service

[Service]
Type=simple
ExecStart=/usr/local/bin/quellog --follow --interval 5m \
  --html -o /var/www/html/quellog.html /var/log/postgresql/*.log
Restart=on-failure
User=postgres

[Install]
WantedBy=multi-user.target

cron -- periodic snapshots without --follow:

0 * * * * /usr/local/bin/quellog --last 1h --html \
  -o /var/www/html/quellog.html /var/log/postgresql/*.log