grep, awk and sed alternatives for python?

Question

os.system(r"grep -R \'Webpage\\|Thumbnail\' tmp | awk -F \' \' \'{print $2}\' | sed \'1~2s/\\(.*\\)/]\\[img]\\1\\[\\/img]\\[\\/URL]/g ; N;s/\\(.*\\)\\n\\(.*\\)/\\2\