Update example in overview section

README.md

@@ -62,41 +62,58 @@ $ echo $?
 $ ls -1 $CACHE_DIR
 1e6b844a49d1850b82feded72cf83ed7_content
 1e6b844a49d1850b82feded72cf83ed7_headers
+cget_log.txt
 $ cat $CACHE_DIR/1e6b844a49d1850b82feded72cf83ed7_headers
 HTTP/1.1 200 OK
-Date: Sat, 29 Oct 2016 18:48:29 GMT
+Date: Wed, 26 Apr 2017 16:29:44 GMT
 Server: Apache
-Last-Modified: Fri, 28 Oct 2016 19:11:49 GMT
-ETag: "1f802b-252f7f2-53ff1a146e740"
+Last-Modified: Tue, 25 Apr 2017 19:14:05 GMT
+ETag: "299866f-54e0286fb789a"
 Accept-Ranges: bytes
-Content-Length: 38991858
-Connection: close
+Content-Length: 43615855
 Content-Type: application/samlmetadata+xml
+
+$ cat $CACHE_DIR/cget_log.txt
+2017-04-26T16:29:44Z cget.sh requesting resource: http://md.incommon.org/InCommon/InCommon-metadata-preview.xml
+2017-04-26T16:30:09Z conditional_get received response code: 200
+2017-04-26T16:30:10Z conditional_get writing cached content file: /tmp/http_cache/1e6b844a49d1850b82feded72cf83ed7_content
+2017-04-26T16:30:10Z conditional_get reading cached content file: /tmp/http_cache/1e6b844a49d1850b82feded72cf83ed7_content
 ```
 
 Assuming the resource doesn't change on the server, subsequent requests will return the cached resource. To bypass the network altogether, use the ``-C`` option:
 
 ```Shell
 $ $BIN_DIR/cget.sh -C $url1 | wc -c
- 38991858
+ 43615855
 ```
 
 Of course the ``-C`` option will fail if the resource is not cached:
 
 ```Shell
-$ $BIN_DIR/cget.sh -C $url2 2> /dev/tty
-ERROR: conditional_get: resource not cached: http://md.incommon.org/InCommon/InCommon-metadata-fallback.xml
+# illustrate "quiet failure mode"
+$ $BIN_DIR/cget.sh -C $url2
 $ echo $?
 1
+$ cat $CACHE_DIR/cget_log.txt | tail -n 2
+2017-04-26T16:39:38Z cget.sh requesting resource: http://md.incommon.org/InCommon/InCommon-metadata-fallback.xml
+2017-04-26T16:39:38Z conditional_get: ERROR: resource not cached: http://md.incommon.org/InCommon/InCommon-metadata-fallback.xml
 ```
 
 OTOH, the ``-F`` option forces the return of a fresh resource from the server. If the resource is cached and unchanged on the server (304), such a request will fail, however:
 
 ```Shell
-$ $BIN_DIR/cget.sh -F $url1 2> /dev/tty
-ERROR: conditional_get: resource not modified: http://md.incommon.org/InCommon/InCommon-metadata-preview.xml
+# again illustrate "quiet failure mode"
+$ $BIN_DIR/cget.sh -F $url1
 $ echo $?
 1
+$ cat $CACHE_DIR/cget_log.txt | tail -n 2
+2017-04-26T16:41:55Z conditional_get received response code: 304
+2017-04-26T16:41:55Z conditional_get: ERROR: resource not modified: http://md.incommon.org/InCommon/InCommon-metadata-preview.xml
+```
+
+The ``-F`` option will work on the other URL, however:
+
+```Shell
 $ $BIN_DIR/cget.sh -F $url2 > /dev/null
 $ echo $?
 0