Create or use an existing fifo, and read commands from it.

vimfifo.sh

#!/bin/bash

VIMFIFO=$1

if [ ! -p "$VIMFIFO" ]; then
	rm -f "$VIMFIFO" && mkfifo "$VIMFIFO"
fi

trap "rm -f '$VIMFIFO'" SIGINT SIGKILL SIGTERM SIGSTOP

clear
while [ -p "$VIMFIFO" ]; do
	read line < "$VIMFIFO"

	if [ -e "$line" ]; then
		continue
	fi

	if [ "$line" = "exit" ]; then
		break
	fi

	clear
	echo "vim> '$line'"
	echo 
	eval "$line"
done

rm -f "$VIMFIFO"