If you look carefully, you can pick out some useful information, such as the file’s format (PNG) and-toward the bottom-the date and time the file was created and last modified. In the right column, you see the same data that’s on the left but presented as ASCII. Just because the default data dump seems meaningless, that doesn’t mean it’s devoid of valuable information. It’s the exact same data you see in an image viewer, encoded in a way that’s probably unfamiliar to you.

What you’re seeing is the contents of the sample PNG file through a lens you may have never used before. For now, you can view your one-pixel graphic in the image viewer of your choice (it looks like this. Coincidentally, that’s what hexdump will reveal. You may wonder how the file command is able to determine what kind of file it is. Pixel.png: PNG image data, 1 x 1, 1-bit grayscale, non-interlaced You can confirm that this file is a PNG with the file command: $ file pixel.png

Here’s a command to generate a 1x1 pixel PNG with ImageMagick: $ convert -size 1x1 canvas:black pixel.png You can do this with a graphics application such as GIMP or Mtpaint, or you can create it in a terminal with ImageMagick. For the purpose of this article, create a 1x1 PNG file. Hexdump provides output with very little effort on your part and depending on the size of the file you’re looking at, there can be a lot of output. It’s a utility for inspection and can be used for data recovery, reverse engineering, and programming. Hexdump is a utility that displays the contents of binary files in hexadecimal, decimal, octal, or ASCII.

Edit contents of bin file