#!/bin/sh
file="$1"
dpi="$2"
[ "$file" ] || exit 1
out="${file%.tex}.png"

makepng() {
    latex -interaction nonstopmode "$file" >/dev/null 2>&1 || return 1
    dvipng -D "$dpi" -T tight -bg Transparent -o  "$out" "${file%.tex}.dvi" >/dev/null 2>&1 || return 1
}

makepng && echo "$out" || exit 1