How to batch export using r.out.gdal command in GRASS

I created a list of files (NPPFILES) using g.mlist command in GRASS 7. Now I would like to export these files as .tiff files. I tried this command in GRASS prompt

for files in $NPPFILES; do
r.out.gdal input="$NPPFILES" output="$NPPFILES.tiff" format=GTiff ; done

This is not working for me. I'm running it in the directory where output files need to be stored, still no result.