What you call "type" is actually a "mapping type" and the way to get them is simply by using:
curl -XGET localhost:9200/_all/_mapping
Now since you only want the names of the mapping types, you don't need to install anything, as you can use simply use Python to only get you what you want out of that previous response:
curl -XGET localhost:9205/_all/_mapping | python -c 'import json,sys; indices=json.load(sys.stdin); indices = [type for index in indices for type in indices.get(index).get("mappings")]; print list(indices);'
The Python script does something very simple, i.e. it iterates over all the indices and mapping types and only retrieves the latter's names:
import json,sys;
resp = json.load(sys.stdin);
indices = [type for index in resp for type in indices.get(index).get("mappings")];
print list(indices);'
UPDATE
Since you're using Ruby, the same trick is available by using Ruby code:
curl -XGET localhost:9205/_all/_mapping | ruby -e "require 'rubygems'; require 'json'; resp = JSON.parse(STDIN.read); resp.each { |index, indexSpec | indexSpec['mappings'].each {|type, fields| puts type} }"
The Ruby script looks like this:
require 'rubygems';
require 'json';
resp = JSON.parse(STDIN.read);
resp.each { |index, indexSpec |
indexSpec['mappings'].each { |type, fields|
puts type
}
}
_typein ES, if you are only interested in types then have a look at @Andrew White's answer here you will need to install jq for that