Specifically, could someone explain what the flags used with the commands are? In the pset4 specs at one point it is mentioned that they use a different value for -c depending upon the number of columns you want to output. I don't understand the values being used with the flags. I am trying to see the hex dump of my images for the resize problem and am having trouble viewing it. Thought maybe I am not using xxd the way its supposed to be used

1 Answer 1


Per xxd's manual page, -c <cols> formats <cols> bytes per line. For example, -c 12 formats 12 bytes per line.

The -g <bytes> groups each <bytes> bytes of the <cols> bytes per each line together. For example, -g 3 groups each 3 bytes of the 12 bytes, in a line, together.

The -s <seek> starts at byte number <seek> from the beginning of the file. For example, -s 54 starts at byte 54 from the beginning of the file.

  • Thanks Kareem! So I used xxd and the pixels of my result seem to match the staff's result on all test cases in Check50 but my code still doesn't pass check50. I don't get any errors with diff either. Could there be anything else Im missing out on? I could post the code/ mail it to you if you want to take a look at it Jun 15, 2015 at 10:10
  • Oh and I checked my headers against the staff's using peek. Nothing there either Jun 15, 2015 at 10:33
  • @sharvarimurthy you may email me with your code along with a link to this question!
    – kzidane
    Jun 15, 2015 at 12:42

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