From OpenSSH 7.3p1, ssh_config has an option IdentityAgent so that I can unset SSH_AUTH_SOCK for invoking ssh with ssh-agent. For example, if I have the following line, you don't have to set SSH_AUTH_SOCK: $ cat $HOME/.ssh/config Host * IdentityAgent ~/.ssh/S.ssh-agent However, ssh-add only looks for SSH_AUTH_SOCK. It would be nice for ssh-add to honor config(s) of IdentityAgent.
ssh-agent doesn't read ~/.ssh/config and we don't have any plans to make it do so.
closing resolved bugs as of 8.6p1 release