# A bug in elasticsearch.yml configuration file. Cannot set an empty string as value

**URL:** <https://discuss.elastic.co/t/a-bug-in-elasticsearch-yml-configuration-file-cannot-set-an-empty-string-as-value/25381>\
**Category:** Elasticsearch\
**Created:** [July 12, 2015, 7:32am UTC](https://discuss.elastic.co/t/a-bug-in-elasticsearch-yml-configuration-file-cannot-set-an-empty-string-as-value/25381 "2015-07-12T07:32:54Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![foresightyj](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/foresightyj/32/3666_2.png) [@foresightyj](https://discuss.elastic.co/u/foresightyj)\
**Post date:** [July 12, 2015, 7:32am UTC](https://discuss.elastic.co/t/a-bug-in-elasticsearch-yml-configuration-file-cannot-set-an-empty-string-as-value/25381/1 "2015-07-12T07:32:54Z")

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_Original title of this post was "A bug in the shingle token filter's token\_separator option, same configuration but different behavior between json and yaml". I changed it to better reflect the nature of the problem. The problem is a general one, not specifically related to the shingle token filter._

I found a weird behavior in the `shingle` token filter. Because the default shingle token filter uses a single space to separate adjacent tokens. I want it to have no space at all. I tested the following analyzer:

```
PUT test_analyzer
{
   "index": {
      "analysis": {
         "analyzer": {
            "my_analyzer": {
               "tokenizer": "standard",
               "filter": [
                  "combiner2"
               ]
            }
         },
         "filter": {
            "combiner2": {
               "max_shingle_size": 2,
               "token_separator": "",
               "type": "shingle"
            }
         }
      }
   }
}

```

Test my\_analyzer with a string "how is it" returns:  
token: how  
token: howis  
token: is  
token: isit  
token: it

However, when I put `combiner2` into `elasticsearch.yml`, and name it `huohuo_combiner2`. as follows:

```
  huohuo_combiner2:
    max_shingle_size: 2
    output_unigrams: true
    token_separator: ""
    type: shingle

```

I then changed the filter definition in the `my_analyzer` definition above to use `huohuo_combiner2` instead. However, the returned token became:

token: how  
token: how is  
token: is  
token: is it  
token: it

Note, there is a space between adjacent tokens even if I set `token_separator` to `""`. If I explicitly set `token_separator` to " " (one space) in `huohuo_combiner2`, the result is the same with one space in tokens. If I set `token_separator` to `" "` (two spaces) in `huohuo_combiner2`, the resultant tokens have two spaces in them.

I tried `''` (two single quotes without space), or not write anything after the colon. All return tokens with one space in them.

Oh, my environment is elasticsearch-1.6.0 in windows 8.

---

<div class="post-metadata">

**Author:** ![foresightyj](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/foresightyj/32/3666_2.png) [@foresightyj](https://discuss.elastic.co/u/foresightyj)\
**Post date:** [July 13, 2015, 8:44am UTC](https://discuss.elastic.co/t/a-bug-in-elasticsearch-yml-configuration-file-cannot-set-an-empty-string-as-value/25381/2 "2015-07-13T08:44:48Z")

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I found something. It is not just the shingle token filter. All keys in elasticsearch.yml, if set to "" or '', will disappear in elasticsearch's actual configuration.

I used `GET /_nodes?os=true&process=true&pretty=true` to get the settings of the node. I found that elasticsearch only gets this much info from my yaml definition:

```
"huohuo_combiner2": {
    "type": "shingle",
    "max_shingle_size": "2"
},

```

It removed the `token_separator` property.

I verified this problem in two windows machines and a linux machine.

---

<div class="post-metadata">

**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, 12:01am UTC](https://discuss.elastic.co/t/a-bug-in-elasticsearch-yml-configuration-file-cannot-set-an-empty-string-as-value/25381/3 "2017-07-06T00:01:53Z")

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