How to copy files from branch to directory in pipeline script bash

[vmunisamy]

Check the following code : 

image:  
  name: vmu/salesforcedockerimg
pipelines:  
  branches:        
    uat:      
      - step:          
          deployment: UAT          
          script:
             - mkdir "src"
             - cd "src"
             - git diff-tree --no-commit-id --name-only -r $BITBUCKET_COMMIT

 I am creating a folder in my working directory call "src", and trying to add only updated files from a commit. I have been able to get the name of the file but NOT the file itself to the directory