The easiest way to show the file size in Terminal in Mac or Linux.
ustins-MacBook-Pro:jpg juzhax$ file 001.jpg 001.jpg: JPEG image data, EXIF standard Justins-MacBook-Pro:jpg juzhax$ identify 001.jpg 001.jpg JPEG 720x468 720x468+0+0 8-bit sRGB 59.8KB 0.000u 0:00.009 Justins-MacBook-Pro:jpg juzhax$