Sandeep,
This might be useless, as it is old. There were problems in the past with using the Google Docs OCR to upload PD
f (and other file types) and get them converted to text, using Google Command line. It was reported as an error in December 2010, as Issue 332 for Google CL project.(Enable OCR for Docs upload):google docs upload does not allow for Docs to apply OCR on the uploaded (scanned) document (either PDF, PNG, JPG)... but it works in the browser
The issue wasn't ever resolved or closed in the Google Cl project, not so as I can see. Take a look at this
Google Cl group discussion by someone else who was having the same problem (I think) as you are with OCR, He asked for help, then figured it out himself and posted his answer in the linked discussion in my previous sentence. The solution seems unlikely because it is so simple, but maybe it is valid.
I hope this isn't a waste of your time. I used to play with (and helped, just a little bit) test GoogleCL in 2011, though I only come back to visit now.
~ Ellie