I am trying to push code from jenkins slave to GitHub, but it saying could not read Password for url

[TR]

I am cloning code into Jenkins slave from GitHub and making few changes and trying to push back to GitHub, but here I am encountering below error :

Here I am setting remote repo as below 

git remote add origin https://$variable@github.com/user/repo.git

Where I assigned user name and password to ' variable '

fatal: could not read Password for 'git-repo-url': No such device or address
Build step 'Execute shell' marked build as failure
Finished: FAILURE

Any help will be appreciated.