Get input file name in streaming hadoop program

Question

I am able to find the name if the input file in a mapper class using FileSplit when writing the program in Java.

Is there a corresponding way to do this when I write

Answer 1

According to the "Hadoop : The Definitive Guide"

Hadoop sets job configuration parameters as environment variables for Streaming programs. However, it replaces non-alphanumeric character with underscores to make sure they are valid names. The following Python expression illustrates how you can retrieve the value of the mapred.job.id property from within a Python Streaming script:

os.environ["mapred_job_id"]

You can also set environment variables for the Streaming process launched by MapReduce by applying the -cmdenv option to the Streaming launcher program (once for each variable you wish to set). For example, the following sets the MAGIC_PARAMETER environment variable:

-cmdenv MAGIC_PARAMETER=abracadabra

Answer 2

By parsing the mapreduce_map_input_file(new) or map_input_file(deprecated) environment variable, you will get the map input file name.

Notice:
The two environment variables are case-sensitive, all letters are lower-case.

Answer 3

The new ENV_VARIABLE for Hadoop 2.x is MAPREDUCE_MAP_INPUT_FILE