I've seen code for virtual domains in the nginx.conf to handle setups with WP Super Cache using an if condition that appears to assign a variable value with "set" as shown in the example below.

Could someone provide me with a link, or links, where I can see some examples of how this is used, how to use set, and what language it is from, so I can write some of my own configurations using this approach?

[code]
# if the requested file exists, return it immediately
if (-f $request_filename) {
break;
}

[b]set $supercache_file '';
set $supercache_uri $request_uri;[/b]

if ($request_method = POST) {
[b]set $supercache_uri '';[/b]
}

# Using pretty permalinks, so bypass the cache for any query string
if ($query_string) {
[b]set $supercache_uri '';[/b]
}

if ($http_cookie ~* "comment_author_|wordpress|wp-postpass_" ) {
[b]set $supercache_uri '';[/b]
}
[/code]