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git fetch origin master
git merge origin master
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git init
git add README.md
git add .
git commit -m "first commit"
git remote add origin https://github.com/userName/repoName.git
git push --force origin master
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git fetch origin master
git merge origin master
git add .
git commit -m 'your commit message'
git push origin master
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git fetch origin master:tmp
git rebase tmp
git push origin HEAD:master
git branch -D tmp