これに合格できません。リポジトリを何度も作り直し、sshキーを作成しました
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demo_app <username>$ git remote add origin git@github.com:<username>/demo_app.git
fatal: remote origin already exists.
$ git push -u origin master
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ssh: Could not resolve hostname git: nodename nor servname provided, or not known
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fatal: Could not read from remote repository.
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Please make sure you have the correct access rights
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and the repository exists.
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Checked ssh keys
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$ ssh -T git@github.com
Hi <username>! You've successfully authenticated, but GitHub does not provide shell access.
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まだ同じメッセージを受信しています。