[BUG]: Error when running sample applications

Describe the bug Encountering this error when running all the .NET sample applications in linux:

20/07/24 22:31:29 WARN Utils: Your hostname, DELL resolves to a loopback address: 127.0.1.1; using 0.0.0.0 instead (on interface eth0)
20/07/24 22:31:29 WARN Utils: Set SPARK_LOCAL_IP if you need to bind to another address
20/07/24 22:31:32 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties
20/07/24 22:31:33 INFO DotnetRunner: Starting DotnetBackend with Microsoft.Spark.CSharp.Examples.
20/07/24 22:31:34 INFO DotnetRunner: Port number used by DotnetBackend is 41987
20/07/24 22:31:34 INFO DotnetRunner: Adding key=spark.jars and value=file:/home/usman/dotnet.spark/src/scala/microsoft-spark-2.4.x/target/microsoft-spark-2.4.x-0.12.1.jar to environment
20/07/24 22:31:34 INFO DotnetRunner: Adding key=spark.app.name and value=org.apache.spark.deploy.dotnet.DotnetRunner to environment
20/07/24 22:31:34 INFO DotnetRunner: Adding key=spark.submit.deployMode and value=client to environment
20/07/24 22:31:34 INFO DotnetRunner: Adding key=spark.master and value=local to environment
20/07/24 22:31:34 ERROR DotnetRunner: Cannot run program "Microsoft.Spark.CSharp.Examples": error=2, No such file or directory
 java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
org.apache.spark.deploy.dotnet.DotnetRunner$.main(DotnetRunner.scala:125)
org.apache.spark.deploy.dotnet.DotnetRunner.main(DotnetRunner.scala)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:498)
org.apache.spark.deploy.JavaMainApplication.start(SparkApplication.scala:52)
org.apache.spark.deploy.SparkSubmit.org$apache$spark$deploy$SparkSubmit$$runMain(SparkSubmit.scala:845)
org.apache.spark.deploy.SparkSubmit.doRunMain$1(SparkSubmit.scala:161)
org.apache.spark.deploy.SparkSubmit.submit(SparkSubmit.scala:184)
org.apache.spark.deploy.SparkSubmit.doSubmit(SparkSubmit.scala:86)
org.apache.spark.deploy.SparkSubmit$$anon$2.doSubmit(SparkSubmit.scala:920)
org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:929)
org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
20/07/24 22:31:34 INFO DotnetRunner: Closing DotnetBackend
20/07/24 22:31:34 INFO ShutdownHookManager: Shutdown hook called
20/07/24 22:31:34 INFO ShutdownHookManager: Deleting directory /tmp/spark-5f105813-1900-4710-92f0-c6fe6cb38c47

To Reproduce

Steps to reproduce the behavior:

1. Follow the instructions set out in this readme
2. Execute this command to run the application as shown in the readme:

spark-submit \
--class org.apache.spark.deploy.dotnet.DotnetRunner \
--master local \
~/dotnet.spark/src/scala/microsoft-spark-2.4.x/target/microsoft-spark-2.4.x-0.12.1.jar \
Microsoft.Spark.CSharp.Examples Sql.Batch.Basic $SPARK_HOME/examples/src/main/resources/people.json

Expected behavior I expect the program to run successfully with no errors.

Desktop (please complete the following information):

• OS: Linux
• Version: Ubuntu 20.04 LTS (WSL)

Additional context Surprisingly program runs successfully when I specify dotnet and reference the project output dll in the command.

spark-submit \
--class org.apache.spark.deploy.dotnet.DotnetRunner \
--master local ~/dotnet.spark/src/scala/microsoft-spark-2.4.x/target/microsoft-spark-2.4.x-0.12.1.jar \
dotnet Microsoft.Spark.CSharp.Examples.dll Sql.Batch.Basic $SPARK_HOME/examples/src/main/resources/people.json

Perhaps this is a case of an outdated readme? Let me know what you think. Thanks.

[usmanmohammed]

Yea this aligns with the *nix behavior. Even if you have an executable in the current directory, you have to prepend the dir (e.g., ./a.out or /home/user/a.out) to execute it unless it’s in PATH.

I think we need to fix README.md. @usmanmohammed, do you want to contribute?

Sure. I’ll open a PR to include the directory prepend for the various commands in the readme.

[imback82]

Great, thanks!