# Beginner issue - testing output to stdout **URL:** \ **Category:** Logstash\ **Created:** [August 18, 2016, 4:32pm UTC](https://discuss.elastic.co/t/beginner-issue-testing-output-to-stdout/58376 "2016-08-18T16:32:47Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Bob\_Metelsky](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/bob_metelsky/32/11387_2.png) [@Bob\_Metelsky](https://discuss.elastic.co/u/Bob_Metelsky)\ **Post date:** [August 18, 2016, 4:32pm UTC](https://discuss.elastic.co/t/beginner-issue-testing-output-to-stdout/58376/1 "2016-08-18T16:32:47Z")
All im basically trying to parse a json file to pick out 2 fields field 1 is name feild 2 is product my ls.conf input { file { type =\> "mefile" path =\> "/export/home/me/me.json" sincedb\_path =\> "/dev/null" } } filter{ json{ source =\> "name" target =\> "thename" source =\> "product" target =\> "theproduct" } } output { stdout { } } I want to output to go to the screen so I can verify the data is what I think. All I get is "pipeline Main started". I've tried removing the filter, expecting the file to be sent to stdout - but still get pipeline main started. final expectation is to only send name and product to ES. HELP! ---
**Author:** ![Bob\_Metelsky](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/bob_metelsky/32/11387_2.png) [@Bob\_Metelsky](https://discuss.elastic.co/u/Bob_Metelsky)\ **Post date:** [August 18, 2016, 4:34pm UTC](https://discuss.elastic.co/t/beginner-issue-testing-output-to-stdout/58376/2 "2016-08-18T16:34:25Z")
Also, Ive spent about 2 hours playing with this 🙂 ---
**Author:** ![magnusbaeck](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/magnusbaeck/32/44943_2.png) [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)\ **Post date:** [August 18, 2016, 5:18pm UTC](https://discuss.elastic.co/t/beginner-issue-testing-output-to-stdout/58376/3 "2016-08-18T17:18:39Z")
Logstash is tailing the input file. Set `start_position => beginning` for the file input. You should also familiarize yourself with its `ignore_older` option. > json{ > source =\> "name" > target =\> "thename" > source =\> "product" > target =\> "theproduct" > } You're misunderstanding how the filter works. The `source` option names the field that should be parsed. In this case each line of the input file will be stored in the `message` field. The json filter will always deserialize the whole JSON message. If you don't want all fields to tag along you can add a prune filter afterwards that removes all fields except the ones you want to keep. ---
**Author:** ![Bob\_Metelsky](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/bob_metelsky/32/11387_2.png) [@Bob\_Metelsky](https://discuss.elastic.co/u/Bob_Metelsky)\ **Post date:** [August 18, 2016, 6:18pm UTC](https://discuss.elastic.co/t/beginner-issue-testing-output-to-stdout/58376/4 "2016-08-18T18:18:56Z")
Ok thank you. How can I get the output to stdout so I can see what's going on? Thanks again ---
**Author:** ![magnusbaeck](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/magnusbaeck/32/44943_2.png) [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)\ **Post date:** [August 18, 2016, 6:21pm UTC](https://discuss.elastic.co/t/beginner-issue-testing-output-to-stdout/58376/5 "2016-08-18T18:21:24Z")
You already have a stdout output so you're all set. Almost; I recommend you use the rubydebug codec for your stdout output so that you see exactly what each event contains: ```nohighlight output { codec => rubydebug } ``` ---
**Author:** ![Bob\_Metelsky](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/bob_metelsky/32/11387_2.png) [@Bob\_Metelsky](https://discuss.elastic.co/u/Bob_Metelsky)\ **Post date:** [August 18, 2016, 11:26pm UTC](https://discuss.elastic.co/t/beginner-issue-testing-output-to-stdout/58376/6 "2016-08-18T23:26:25Z")
Very nice thank you! Can you give a hint or more about pulling just a few fields out of the message? ---
**Author:** ![Bob\_Metelsky](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/bob_metelsky/32/11387_2.png) [@Bob\_Metelsky](https://discuss.elastic.co/u/Bob_Metelsky)\ **Post date:** [August 18, 2016, 11:36pm UTC](https://discuss.elastic.co/t/beginner-issue-testing-output-to-stdout/58376/7 "2016-08-18T23:36:29Z")
If I add this filter its even sweeter! very nice filter{ json{ source =\> "message" } ```auto here are the feilds of interest... "@version" => "1", "@timestamp" => "2016-08-18T23:31:48.155Z", "path" => "..d...d", "host" => "hostname", "type" => "PUREPATH", "name" => " _BrowserType_SPLT_BT", "application" => "UCFE2 Application", "purePathId" => "PT=478227;PA=-727720757;PS=1336977021", "startTime" => "2016-08-06 00:52:04.757-0400", "dimensions" => { "nameBrowserType_SPLT_MSR" => "IE" }, "failed" => false, "responseTime" => 901.0671997070312, "duration" => 901.067138671875, "cpuTime" => 790.1187744140625, "execTime" => 901.0671709775925, "suspensionTime" => 18.81926155090332, "waitTime" => 11.579818453107563 say I only need 3 (prune) ??? ``` ---
**Author:** ![magnusbaeck](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/magnusbaeck/32/44943_2.png) [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)\ **Post date:** [August 19, 2016, 6:19am UTC](https://discuss.elastic.co/t/beginner-issue-testing-output-to-stdout/58376/8 "2016-08-19T06:19:53Z")
> say I only need 3 (prune) ??? Add a prune filter that sets the `whitelist_names` option to a list of the fields you want to keep. Keep in mind that the strings in the last are interpreted as regular expressions. ---
**Author:** ![Bob\_Metelsky](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/bob_metelsky/32/11387_2.png) [@Bob\_Metelsky](https://discuss.elastic.co/u/Bob_Metelsky)\ **Post date:** [August 19, 2016, 12:32pm UTC](https://discuss.elastic.co/t/beginner-issue-testing-output-to-stdout/58376/9 "2016-08-19T12:32:36Z")
Ok I will try that today, thanks you have been immensely helpful to get me going ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 4:42am UTC](https://discuss.elastic.co/t/beginner-issue-testing-output-to-stdout/58376/10 "2017-07-06T04:42:32Z")