How to Using SSH Key on Github Project Existing ?

If have you got a github project existing and you want using ssh key for push or pull data on repository. You can follow below steps for problem solving:

Environment variable GIT_SSH_COMMAND

From Git version 2.3.0, you can use the environment variable GIT_SSH_COMMAND like this:

GIT_SSH_COMMAND="ssh -i ~/.ssh/id_rsa_example" git clone example

Note that -i can sometimes be overridden by your config file, in which case, you should give SSH an empty config file, like this:

GIT_SSH_COMMAND="ssh -i ~/.ssh/id_rsa_example -F /dev/null" git clone git@github.com:example/example.git

Configuration core.sshCommand

Since Git version 2.10.0, you can configure this per repo or globally, using the core.sshCommand setting. There's no more need to use the environment variable. Here's how you clone a repo and set this configuration at the same time:

git clone -c "core.sshCommand=ssh -i ~/.ssh/id_rsa_example -F /dev/null" git@github.com:example/example.git
cd example/
git pull
git push

If the repo already exists, run:

git config core.sshCommand "ssh -i ~/.ssh/id_rsa_example -F /dev/null"

The configuration is saved in .git/config

Reference article : https://superuser.com/questions/232373/how-to-tell-git-which-private-key-to-use

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