CODEWITHSUNDEEP
perlbinarysedhexreplace
Ryan
Ryan

Reputation: 3619

binary sed replacement

I was attempting to do a sed replacement in a binary file however I am beginning to believe that is not possible. Essentially what I wanted to do was similar to the following:

sed -bi "s/\(\xFF\xD8[[:xdigit:]]\{1,\}\xFF\xD9\)/\1/" file.jpg

The logic I wish to achieve is: scan through a binary file until the hex code FFD8, continue reading until FFD9, and only save what was between them (discards the junk before and after, but include FFD8 and FFD9 as the saved part of the file)

Is there a good way to do this? Even if not using sed?

EDIT: I just was playing around and found the cleanest way to do it IMO. I am aware that this grep statement will act greedy.

hexdump -ve '1/1 "%.2x"' dirty.jpg | grep -o "ffd8.*ffd9" | xxd -r -p > clean.jpg

Upvotes: 35

Views: 48064

Answers (6)

h5v
h5v

Reputation: 9

sed -i "s/$(python -c "print('\x1f', end='')")/;/g" file

Upvotes: 0

recette
recette

Reputation: 133

Old question, but,

xxd infile | sed 's/xxxx xxxx/yyyy yyyy/' | xxd -r > outfile

is probably the simplest and most reliable solution. Similar to the edit in the OP.

Upvotes: 9

Ivan Tarasov
Ivan Tarasov

Reputation: 7407

bbe is a "sed for binary files", and should work more efficiently for large binary files than hexdumping/reconstructing.

An example of its use:

$ bbe -e 's/original/replaced/' infile > outfile

Further information on the man page.

Upvotes: 53

DVK
DVK

Reputation: 129549

Also, this Perl might work (not tested, caveat emptor)... if Python is not installed :)

open(FILE, "file.jpg") || die "no open $!\n";
while (read(FILE, $buff, 8 * 2**10)) {
    $content .= $buff;
}
@matches = ($content =~ /(\xFF\xD8[:xdigit:]+?\xFF\xD9)/g;
print STDOUT join("", @matches);

You need to add binmode(FILE); binmode(STDOUT); on DOS or VMS after the open() call - not needed on Unix.

Upvotes: 1

ghostdog74
ghostdog74

Reputation: 343135

Is there a good way to do this

yes of course, use an image editing tool such as those from ImageMagick (search the net for linux jpeg , exif editor etc) that knows how to edit jpg metadata. I am sure you can find one tool that suits you. Don't try to do this the hard way. :)

Upvotes: 2

Adam Rosenfield
Adam Rosenfield

Reputation: 400652

sed might be able to do it, but it could be tricky. Here's a Python script that does the same thing (note that it edits the file in-place, which is what I assume you want to do based on your sed script):

import re

f = open('file.jpeg', 'rb+')
data = f.read()
match = re.search('(\xff\xd8[0-9A-fa-f]+)\xff\xd9', data)
if match:
    result = match.group(1)
    f.seek(0)
    f.write(result)
    f.truncate()
else:
    print 'No match'
f.close()

Upvotes: 2

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