Monster's questions

I am trying to use the best model from tesseract. However, I am getting the following error:

tesseract sample.jpg stdout --tessdata-dir tessdata/
Error opening data file tessdata/eng.traineddata
Please make sure the TESSDATA_PREFIX environment variable is set to your "tessdata" directory.
Failed loading language 'eng'
Tesseract couldn't load any languages!
Could not initialize tesseract.

Here is the folder structure: .

├── sample.jpg
└── tessdata
    └── eng.traineddata

Ubuntu Version:
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.1 LTS
Release:        18.04
Codename:       bionic
tesseract version:
tesseract 4.0.0-beta.1
 leptonica-1.75.3
  libgif 5.1.4 : libjpeg 8d (libjpeg-turbo 1.5.2) : libpng 1.6.34 : libtiff 4.0.9 : zlib 1.2.11 : libwebp 0.6.1 : libopenjp2 2.3.0