ssh(1) -i ~/.ssh/
OpenSSH SSH client (remote login program)
-i identity_file
        Selects a file from which the identity (private key) for public key authentication is read.  The
        default is ~/.ssh/identity for protocol version 1, and ~/.ssh/id_dsa, ~/.ssh/id_ecdsa and
        ~/.ssh/id_rsa for protocol version 2.  Identity files may also be specified on a per-host basis in
        the configuration file.  It is possible to have multiple -i options (and multiple identities
        specified in configuration files).  ssh will also try to load certificate information from the
        filename obtained by appending to identity filenames.
ssh connects and logs into the specified hostname (with optional user name).  The user must prove his/her
identity to the remote machine using one of several methods depending on the protocol version used (see

If command is specified, it is executed on the remote host instead of a login shell.
source manpages: ssh