EDIT: to make this question more specific. Please provide "hello world" example of executing sparql query over .ttl file locally on Linux using tool of your choice.
csvsql allows to query .csv files directly (i.e., without importing) via SQL; for example:
$ csvsql --query "select m.usda_id, avg(i.sepal_length) as
mean_sepal_length from iris as i join irismeta as m on (i.species =
m.species) group by m.species" examples/iris.csv examples/irismeta.csv
I would love to have similar ability to query with SPARQL over Turtle .ttl or other typical RDF files.
How to achieve similar "one-off" "direct query" functionality for SPARQL and Turtle or similar files?
(e.g., small script that loads given file into memory of, e.g., running blazegraph instance, and runs query returns result and withdraws what's in memory; or maybe something using librdf, e.g., Rasqal/Redland or Neo4j or any other SPARQL implementation - preferably something without running background instance, one-off, KISS)
IMHO such tool would be great for hobbyists and enthusiasts who may want to play with storing data in triples and querying it without launching full server. It would be also VERY beneficial to education purposes.
Could you provide specific example, backed by snippet, showing how to do this? (locally on Linux)
Rasqal's command-line query tool roqet does this; see http://librdf.org/rasqal/roqet.html.
Or online at http://triplr.org/query.
Edit with example how it works and packages:
Rasqal example packages:
Let's try to perform "hello world" query from : https://wiki.blazegraph.com/wiki/index.php/Quick_Start tutorial.
Here is example data.ttl file:
PREFIX : <http://blazegraph.com/>
PREFIX schema: <http://schema.org/>
:systap a schema:Organization ;
schema:owns :blazegraph .
:blazegraph a schema:Product ;
schema:brand :systap;
:productOf <http://systap.com/>;
:implements <http://rdf4j.org>,<http://blueprints.tinkerpop.com> .
And example "hello world" Sparql queries:
$ roqet -i sparql -e 'SELECT * WHERE { <http://blazegraph.com/blazegraph> ?p ?o }' -D data.ttl
roqet: Running query 'SELECT * WHERE { <http://blazegraph.com/blazegraph> ?p ?o }'
roqet: Query has a variable bindings result
row: [p=uri<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>, o=uri<http://schema.org/Product>]
row: [p=uri<http://schema.org/brand>, o=uri<http://blazegraph.com/systap>]
row: [p=uri<http://blazegraph.com/productOf>, o=uri<http://systap.com/>]
row: [p=uri<http://blazegraph.com/implements>, o=uri<http://rdf4j.org>]
row: [p=uri<http://blazegraph.com/implements>, o=uri<http://blueprints.tinkerpop.com>]
roqet: Query returned 5 results
or even more generic
$ roqet -i sparql -e 'SELECT * WHERE { ?s ?p ?o }' -D data.ttl | xsel -b
roqet: Running query 'SELECT * WHERE { ?s ?p ?o }'
roqet: Query has a variable bindings result
row: [s=uri<http://blazegraph.com/systap>, p=uri<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>, o=uri<http://schema.org/Organization>]
row: [s=uri<http://blazegraph.com/systap>, p=uri<http://schema.org/owns>, o=uri<http://blazegraph.com/blazegraph>]
row: [s=uri<http://blazegraph.com/blazegraph>, p=uri<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>, o=uri<http://schema.org/Product>]
row: [s=uri<http://blazegraph.com/blazegraph>, p=uri<http://schema.org/brand>, o=uri<http://blazegraph.com/systap>]
row: [s=uri<http://blazegraph.com/blazegraph>, p=uri<http://blazegraph.com/productOf>, o=uri<http://systap.com/>]
row: [s=uri<http://blazegraph.com/blazegraph>, p=uri<http://blazegraph.com/implements>, o=uri<http://rdf4j.org>]
row: [s=uri<http://blazegraph.com/blazegraph>, p=uri<http://blazegraph.com/implements>, o=uri<http://blueprints.tinkerpop.com>]
roqet: Query returned 7 results