Hadoop Pig: Passing Command Line Arguments

Question

Is there a way to do this? eg, pass the name of the file to be processed, etc?

Answer 1

This showed up in another question, but you can indicate the input parameter on the command line and use that when you are loading, for example:

Command Line:

pig -f script.pig -param input=somefile.txt

script.pig:

raw = LOAD '$input' AS (...);

Note that if you are using the Amazon Web Services Elastic Map Reduce then the '$input' is what is passed to the script for any input you provide.

Answer 2

You can use ...
1. if there are few parameters then use -param (-p)
2. if there are lot of parameters then use -param_file (-m)

You can use either approach depending on the nature of value of your command line arguments, I use -param when i am developing and testing my scripts. Once pig script is ready for batch processing or running thru crontab, I use -param_file so that if any change required, I can easily update the params.init file.

man pig will show you all available options.

-m, -param_file path to the parameter file
-p, -param key value pair of the form param=val

Here is sample code ...

students.txt (input data)

001,Rajiv,Reddy,21,9848022337,Hyderabad
002,siddarth,Battacharya,22,9848022338,Kolkata
003,Rajesh,Khanna,22,9848022339,Delhi
004,Preethi,Agarwal,21,9848022330,Pune
005,Trupthi,Mohanthy,23,9848022336,Bhuwaneshwar
006,Archana,Mishra,23,9848022335,Chennai
007,Komal,Nayak,24,9848022334,trivendram
008,Bharathi,Nambiayar,24,9848022333,Chennai

params.init (file to hold all parameters)

fileName='hdfs://horton/user/jgosalia/students.txt'
cityName='Chennai'

filter.pig

students = LOAD '$fileName' USING PigStorage(',') AS (id:int, firstname:chararray, lastname:chararray, age:int, phone:chararray, city:chararray);
students = FILTER students BY city == '$cityName';
DUMP students;

OPT 1: Using params on command line (-param or -p) & Output

pig -param fileName='hdfs://horton/user/jgosalia/students.txt' -param cityName='Chennai' filter.pig

... Trimming the logs ...

(6,Archana,Mishra,23,9848022335,Chennai)
(8,Bharathi,Nambiayar,24,9848022333,Chennai)

OPT 2: Using params file on command line (-param_file or -m) & Output

pig -param_file params.init filter.pig

... Trimming the logs ...

(6,Archana,Mishra,23,9848022335,Chennai)
(8,Bharathi,Nambiayar,24,9848022333,Chennai)

NOTE: use absolute path for file paths (both as parameters and when giving param file path to -param_file (-m)).

Answer 3

It is simple to pass in parameters to a PIG script.

First mark your variables in pig using '$' for example $input_file. Then pass the parameters to you script using pig -params input_file='/path/to/data'

for more information look here: http://wiki.apache.org/pig/ParameterSubstitution

Answer 4

Yes.

You can pass parameters along commandline options using pig's param option.

--customparam.pig
--load hdfs/local fs data 
 original = load '$input' using PigStorage('$delimiter');
--filter a specific field value into another bag  
 filtered = foreach original generate $split; 
--storing data into hdfs/local fs 
  store filtered into '$output';

pig -x local -f customparam.pig -param input=Pig.csv -param output=OUT/pig -param delimiter="," -param split='$1'

For more info: check this