How would I go about truncating a binary file when a certain pattern is found?

For instance, I want to truncate the file at the first occurrence of the pattern 0xFFFFFFFF.

I think something like awk could do the trick... but I'm not exactly sure how.


2 Answers 2


Convert to octal and assign to the record separator.

awk 'BEGIN{RS="\377\377\377\377"} NR==1 {print;exit}'

I'm quite sure, it's possible using Perl when you do the following

  • use the command line option -0777 to slurp all the input at once
  • use Latin-1 coding
  • use s/\xFF\xFF\xFF\xFF.*//s

I did something like this a long time ago, but I don't recall the options anymore. For awk I have no idea.

  • Oh, awk is not a requirement, any solution will do. I'm not very good at Perl, could you provide a simple example?
    – nico
    Mar 1, 2011 at 12:52
  • 1
    Something like perl -0777 -pe 's/\xFF\xFF\xFF\xFF.*//s' < infile > outfile, but I don't know how to set the encoding now.
    – maaartinus
    Mar 1, 2011 at 13:25

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