How do I get schema / column names from parquet file?

You won't be able "open" the file using a hdfs dfs -text because its not a text file. Parquet files are written to disk very differently compared to text files.

And for the same matter, the Parquet project provides parquet-tools to do tasks like which you are trying to do. Open and see the schema, data, metadata etc.

Check out the parquet-tool project (which is put simply, a jar file.)parquet-tools

Also Cloudera which support and contributes heavily to Parquet, also has a nice page with examples on usage of parquet-tools. A example from that page for your use case is

parquet-tools schema part-m-00000.parquet

Checkout the Cloudera page. Using the Parquet File Format with Impala, Hive, Pig, HBase, and MapReduce

If your Parquet files are located in HDFS or S3 like me, you can try something like the following:

HDFS

parquet-tools schema hdfs://<YOUR_NAME_NODE_IP>:8020/<YOUR_FILE_PATH>/<YOUR_FILE>.parquet

S3

parquet-tools schema s3://<YOUR_BUCKET_PATH>/<YOUR_FILE>.parquet

Hope it helps.

If you use Docker you can also run parquet-tools in a container:

docker run -ti -v C:\file.parquet:/tmp/file.parquet nathanhowell/parquet-tools schema /tmp/file.parquet