Display Varnish logs. More information: https://varnish-cache.org/docs/trunk/reference/varnishlog.html.
varnishlog
varnishlog -q 'ReqHeader eq "Host: example.com"'
varnishlog -q 'ReqMethod eq "POST"'
varnishlog -q 'ReqURL eq "/path"'
varnishlog -q 'ReqURL ~ "regex"'