github官方操作文档：Generating a new SSH key and adding it to the ssh-agent - GitHub Docs
操作流程如下
1.生成一个新的ssh文件（your_email@example.com 替换为自己的邮箱）
ssh-keygen -t ed25519 -C "your_email@example.com"
# 如果系统不支持 Ed25519 算法，可以使用下面方法创建
# ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
# 如果需要给秘钥设置密码，也可以在这两步的时候，设置密码
> Enter passphrase (empty for no passphrase): [Type a passphrase]
> Enter same passphrase again: [Type passphrase again]2.添加公钥到github
复制公钥内容到剪贴板
打开浏览器，登录github.com ,右上角，点击settings
?找到 SSH and GPG keys ,点击进入
?点击添加
?
?测试权限是否正常，能否通过ssh访问git
ssh -T git@github.com?a.访问成功如下：
b.访问失败如下：
?访问失败，需要检查公钥文件是否添加到github
其他机器通过指定秘钥文件访问【方式一】?
?1.创建目录，并拷贝秘钥文件该目录下，并修改为0600权限
mkdir -pv ~/.ssh_git
# 将私钥文件拷贝到该目录，并修改权限
chmod 0600 -R ~/.ssh_git2.启动ssh-agent代理，并添加私钥，然后进行测试
eval "$(ssh-agent -s)"
ssh-add ~/.ssh_git/id_ed25519
ssh -T git@github.com
当ssh-agent进程结束时，将失去访问权限，若想继续访问，还需要重新执行操作
?
?重新添加私有执行
?其他机器通过指定秘钥文件访问【方式二】?
通过 .gitconfig 配置文件进行配置，该配置针对git命令
core.sshCommand
If this variable is set,?git fetch?and?git push?will use the specified command instead of?ssh?when they need to connect to a remote system. The command is in the same form as the?GIT_SSH_COMMAND?environment variable and is overridden when the environment variable is set.
git config --global core.sshCommand 'ssh -i ~/.ssh_git/id_ed25519 -p 22'该操作会在用户家目录自动生成.gitconfig配置文件,内容如下
测试，需要指定克隆私有仓库进行测试，下图表示测试成功
?其他机器通过指定秘钥文件访问【方式三】?
通过?GIT_SSH_COMMAND 环境变量实现访问
?$GIT_SSH_COMMAND?takes precedence over?$GIT_SSH, and is interpreted by the shell, which allows additional arguments to be included.?$GIT_SSH?on the other hand must be just the path to a program (which can be a wrapper shell script, if additional arguments are needed).
export GIT_SSH_COMMAND="ssh -i ~/.ssh_git/id_ed25519 -p 22"
注意：GIT_SSH_COMMAND? 的优先权大于?GIT_SSH
通过?GIT_SSH 环境变量实现访问
? ? ? GIT_SSH, if specified, is a program that is invoked instead of ssh when Git tries to connect to an SSH host. It is invoked like $GIT_SSH [username@]host [-p <port>] <command>. Note that this isn’t the easiest way to customize how ssh is invoked; it won’t support extra command-line parameters, so you’d have to write a wrapper script and set GIT_SSH to point to it. It’s probably easier just to use the ~/.ssh/config file for that.
?大概意思指定了 GIT_SSH ,则当git通过ssh连接主机是，调用GIT_SSH设置的脚本来替换默认的ssh命令
1.创建一个文件，内容如下?~/.ssh_git/ssh-git.sh
vim ~/.ssh_git/ssh-git.sh#!/bin/bash
if [ -z "$PKEY" ]; then
# if PKEY is not specified, run ssh using default keyfile
ssh "$@"
else
ssh -i "$PKEY" -p 22 "$@"
fi
2.添加可执行权限
chmod a+x ~/.ssh_git/ssh-git.sh3.通过添加私有方式进行访问
export GIT_SSH=~/.ssh_git/ssh-git.sh
PKEY=~/.ssh_git/id_ed25519 git clone git@github.com:nineaiyu/scorems.git
?4.整理上面操作步骤，可总结一个脚本git.sh，内容如下：
#!/bin/bash
#
if [ $# -eq 0 ]; then
echo "git.sh -i ssh-key-file git-command"
exit 1
fi
git_ssh_tmp=~/.git_ssh.tmp
trap "rm -f ${git_ssh_tmp}" 0
if [ "$1" = "-i" ]; then
SSH_KEY=$2
shift
shift
echo "ssh -i $SSH_KEY -p 22 \$@" > ${git_ssh_tmp}
chmod +x ${git_ssh_tmp}
export GIT_SSH=${git_ssh_tmp}
fi
[ "$1" = "git" ] && shift
git "$@"执行操作如下：
chmod a+x git.sh
./git.sh -i ~/.ssh_git/id_ed25519 clone git@github.com:nineaiyu/scorems.git
?