ssh-agent.win10-bridged

#!/bin/sh
SSH_AUTH_SOCK=`mktemp -u /tmp/ssh-agent.XXXXXXXXX`

nohup  socat </dev/null >/dev/null 2>&1  UNIX-LISTEN:$SSH_AUTH_SOCK,umask=066,fork EXEC:"npiperelay -ei //./pipe/openssh-ssh-agent",pipes &
SSH_AGENT_PID=$! 
disown -ah 

if [ -z ${1+x} ]; then
	echo "SSH_AUTH_SOCK=$SSH_AUTH_SOCK;export SSH_AUTH_SOCK;"
	echo "SSH_AGENT_PID=$SSH_AGENT_PID; export SSH_AGENT_PID;"
	echo "echo Agent pid $SSH_AGENT_PID;"
	exit 0
else
	(tail --pid $$ -f /dev/null; kill $SSH_AGENT_PID) &
	SSH_AUTH_SOCK=$SSH_AUTH_SOCK exec $*
fi

Needs https://github.com/jstarks/npiperelay. Also works with putty plink. See https://superuser.com/questions/1526348/share-ssh-agent-socket-or-any-other-named-pipe-between-windows-10-and-cygwin