We can check the syntax of varnish configuration, through command line. This will be very helpful while doing custom configurations in varnish.
The command for checking the syntax is,
#varnishd -C -f /usr/local/varnish/etc/varnish/default.vcl
If everything is correct, varnish will then dump out the generated configuration. Otherwise you’ll get an error message pointing you to a specific line number.