varnishlog

Show live logs

$ varnishlog

$ varnishlog -I [ReqURL]

$ varnishlog -q "[RespStatus == 500]"

$ varnishlog -c

$ varnishlog -b

$ varnishlog -g request

varnishlog [-c] [-b] [-q query] [-I tag] [options]

varnishlog reads the Varnish Shared Memory Log (VSL) and displays detailed request and response information in real time. It shows the full lifecycle of HTTP transactions including client requests, backend fetches, cache decisions, and response headers.
The tool provides powerful filtering through the VSL query language, allowing you to isolate specific transactions by status code, URL pattern, or any logged field. Client-side (-c) and backend-side (-b) views can be shown independently, and grouping modes organize output by request, session, or raw log entries. This makes it the primary debugging tool for understanding Varnish cache behavior.

-c

Client side.

Backend side.

VSL query.

Include tag.

Grouping mode.

Process old entries.

Varnish specific. VSL knowledge helpful. Running Varnish needed.

varnishlog is part of Varnish Cache, displaying the Varnish Shared Memory Log for debugging.

varnishhist(1), varnishstat(1), varnishd(1)