How to check if a large binary file contains the contents of another one?

Question

I have a large binary file e.g. a WAV file which I suspect might contain the whole sequence of bytes of a smaller WAV file.

How do I check if it does? If it does, how do I find the starting position?

Something like:

$ findguts big.wav small.wav
1234 # the contents of small.wav are found inside big.wav starting at byte #1234

Stéphane Chazelas · Accepted Answer · 2020-11-24 13:00:07Z

3

With perl:

perl -l -0777 -ne '
  print "found at offset $o" if ($o = index($_, <STDIN>)) >= 0
  ' big.wav < small.wav

(note that both files are loaded in memory, so it doesn't scale to very large files).

answered Nov 24 '20 at 13:00

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2

Probably, we should consider the header of such files, e.g. for WAV I see that first 44 bytes is the header, which is file dependent (e.g. last part is the file size) so it seems meaningful to exclude it before search, with a tail or anything. (without having any idea about the wav format) – thanasisp Nov 24 '20 at 13:09

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