Environment Variables (SSH, The Secure Shell: The Definitive Guide)

B.11. Environment Variables

Variable	Set By	In	Meaning
SSH_AUTH_SOCK	ssh-agent	SSH1, OpenSSH	Path to socket
SSH2_AUTH_SOCK	ssh-agent	SSH2	Path to socket
SSH_CLIENT	sshd	SSH1, OpenSSH	Socket info
SSH2_CLIENT	sshd	SSH2	Socket info
SSH_ORIGINAL_COMMAND	sshd	SSH1	Client's remote command string
SSH_SOCKS_SERVER	sshd	SSH2	SOCKS firewall information
SSH_TTY	sshd	SSH1, OpenSSH	Name of allocated TTY
SSH2_TTY	sshd	SSH2	Name of allocated TTY