Snappy compressed file on HDFS appears without extension and is not readable - bash

Question

I configured a Map Reduce job to save output as a Sequence file compressed with Snappy. The MR job executes successfully however in HDFS the output file looks as the following:
I've expected that the file will have a .snappy extension and that it should be part-r-00000.snappy. And now I think that this may be the reason for the file to be not readable when I'm trying to read it from a local file system using this pattern hadoop fs -libjars /path/to/jar/myjar.jar -text /path/in/HDFS/to/my/file
So I'm getting the –libjars: Unknown command when executing the command:
hadoop fs –libjars /root/hd/metrics.jar -text /user/maria_dev/hd/output/part-r-00000
And when I'm using this command hadoop fs -text /user/maria_dev/hd/output/part-r-00000, I'm getting the error:
18/02/15 22:01:57 INFO compress.CodecPool: Got brand-new decompressor [.snappy]
-text: Fatal internal error
java.lang.RuntimeException: java.io.IOException: WritableName can't load class: com.hd.metrics.IpMetricsWritable
Caused by: java.lang.ClassNotFoundException: Class com.hd.ipmetrics.IpMetricsWritable not found
Could it be that the absence of the .snappy extension causes the problem? What other command should I try to read the compressed file?
The jar is in my local file system /root/hd/ Where should I place it not to cause ClassNotFoundException? Or how should I modify the command?

Answer 1

Instead of hadoop fs –libjars (which actually has a wrong hyphen and should be -libjars. Copy that exactly, and you won't see Unknown command)
You should be using HADOOP_CLASSPATH environment variable
export HADOOP_CLASSPATH=/root/hd/metrics.jar:${HADOOP_CLASSPATH}
hadoop fs -text /user/maria_dev/hd/output/part-r-*

Answer 2

The error clearly says ClassNotFoundException: Class com.hd.ipmetrics.IpMetricsWritable not found.
It means that a required library is missing in classpath.
To clarify your doubts:
Map-Reduce by default output the file as part-* and there is no
meaning of extension. Remember extension "thing" is just a metadata
usually required by windows operating system to determine suitable
program for the file. It has no meaning in linux/unix and the
system's behavior is not going to change, even though you rename the
file as .snappy (you may actually try this).
The command looks absolutely fine to inspect the snappy file, but it seems that some required jar file are not there, which is causing ClassNotFoundException.
EDIT 1:
By default hadoop picks the jar files from the path emit by below command:
$ hadoop classpath
By default it list all the hadoop core jars.
You can add your jar by executing below command on the prompt
export HADOOP_CLASSPATH=/path/to/my/custom.jar
After executing this, try checking the class path again by hadoop classpath command and you should be able to see your jar listed along with hadoop core jars.