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+Usage
+=====
+
+When using the CDP-based remote agent in Firefox, there are
+three different programs/components running simultaneously:
+
+ * the __client__, being the out-of-process script or library
+ (such as Puppeteer) or web inspector frontend you use to control
+ and retrieve information out of Firefox;
+
+ * the __agent__ that the client connects to which is an HTTPD living
+ inside Firefox, facilitating communication between clients
+ and targets;
+
+ * and the __target__, which is the web document being debugging.
+
+The remote agent ships in [Firefox Nightly] only.
+
+To check if your Firefox binary has the remote agent enabled, you
+can look in its help message for this:
+
+ % ./firefox -h
+ …
+ --remote-debugging-port [<port>] Start the Firefox remote agent, which is
+ a low-level debugging interface based on the CDP protocol.
+ Defaults to listen on localhost:9222.
+ …
+
+When used, the remote agent will start an HTTP server and print a
+message on stderr with the location of the main target’s WebSocket
+listener:
+
+ % firefox --remote-debugging-port
+ DevTools listening on ws://localhost:9222/devtools/browser/7b4e84a4-597f-4839-ac6d-c9e86d16fb83
+
+`--remote-debugging-port` takes an optional port as input:
+
+ [<port>]
+
+You can use this to instruct the remote agent to bind to a particular
+port on your system. port is optional,
+which means `firefox --remote-debugging-port` will bind the HTTPD to
+the default `localhost:9222`.
+
+If port has been specified the default port will be overridden:
+
+ % firefox --remote-debugging-port 9989
+ DevTools listening on ws://localhost:9989/devtools/browser/b49481af-8ad3-9b4d-b1bf-bb0cdb9a0620
+
+When you ask the remote agent to listen on port 0,
+the system will atomically allocate an arbitrary free port:
+
+ % firefox --remote-debugging-port 0
+ DevTools listening on ws://localhost:59982/devtools/browser/a12b22a9-1b8b-954a-b81f-bd31552d3f1c
+
+Allocating an atomic port can be useful if you want to avoid race
+conditions. The atomically allocated port will be somewhere in the
+ephemeral port range, which varies depending on your system and
+system configuration, but is always guaranteed to be free thus
+eliminating the risk of binding to a port that is already in use.
+
+[Firefox Nightly]: https://www.mozilla.org/en-GB/firefox/channel/desktop/#nightly