Unix binary file difference

Many do, at least begin with a magic string. Rikki Rikki 1, 14 14 silver badges 17 17 bronze badges. Can you explain your down votes please? SHA1 has 4 upvotes, and if the OP thinks there's a chance the two files could be the same or similar, the chances of a collision are slight and not worthy of down voting MD5 but up voting SHA1 other than because you heard you should hash your passwords with SHA1 instead of MD5 that's a different problem.

I downvoted because you posted a minor variant of an earlier bad solution, when it should have been a comment. The quickest way to check large files : Thanks a lot — Sumeet Patil. This is exactly what I found using URL to manual that you have provided.

Victor Yarema, I don't know what you mean by "binary mode". The -b option merely prints the first byte that is different. For finding flash memory defects, I had to write this script which shows all 1K blocks which contain differences not only the first one as cmp -b does! Daniel Alder Daniel Alder 4, 1 1 gold badge 43 43 silver badges 49 49 bronze badges.

Please call the script using sh -x for debugging — Daniel Alder. This is via calling the script from terminal. Line is 9. The script is ok. Please post your debug output to pastebin. You can see here what I mean: pastebin. Currently creating paste on pastebin. Show 3 more comments. DKroot DKroot 1, 13 13 silver badges 22 22 bronze badges.

Try diff -s Short answer: run diff with the -s switch. Long answer: read on below. Here's an example. Why is there no output?!? The answer is: this is by design. There is no output on identical files. Community Bot 1 1 1 silver badge. For instance, with this command: radiff2 -x file1. My favourite ones using xxd hex-dumper from the vim package : 1 using vimdiff part of vim!

Michal Ambroz Michal Ambroz 2 2 bronze badges. Not quite. Only the possibility is high. What is the probability of failing? Slim, but worse than using some variant of diff , over which there is no reason to prefer it. Anyone's laptop can these days generate collision in MD5 and based on this single collision prefix 2 files of the same size, same prefix and same MD5 to generate infinite number of colliding files having same prefix, different colliding block, same suffix — Michal Ambroz.

But with details if you're interested in those. Which is helpful for doing reverse Engineering. Optionally list and search all diff. So it used a very small amount of storage space. Francewhoa Francewhoa 11 3 3 bronze badges.

There is a relatively simple way to check if two binary files are the same. At this point the check is as simple as : if file1! So, the question is, how do you tell if a file is 'text' or 'binary'?

And to restrict is further, how do you tell on a Linux like file-system? I am not aware of any filesystem meta-data that indicates the 'type' of a file, so the question further becomes, by inspecting the content of a file, how do I tell if it is 'text' or 'binary'?

And for simplicity, lets restrict 'text' to mean characters which are printable on the user's console. And in particular how would you implement this? I thought this was implied on this site, but I guess it is helpful, in general, to be pointed at existing code that does this, I should have specified , I'm not really after what existing programs can I use to do this.

You can use the file command. It does a bunch of tests on the file man file to decide if it's binary or text. You can determine the MIME type of the file with. The shorthand is file -i on Linux and file -I capital i on macOS see comments.

The only exception are XML applications. The spreadsheet software my company makes reads a number of binary file formats as well as text files. We first look at the first few bytes for a magic number which we recognize. If we do not recognize the magic number of any of the binary types we read, then we look at up to the first 2K bytes of the file to see whether it appears to be a UTF-8 , UTF or a text file encoded in the current code page of the host operating system. If it passes none of these tests, we assume that it is not a file we can deal with and throw an appropriate exception.

Well, if you are just inspecting the entire file, see if every character is printable with isprint c. It gets a little more complicated for Unicode. To distinguish a unicode text file, MSDN offers some great advice as to what to do. That will tell you the encoding. Then, you'd want to use iswprint c for the rest of the characters in the text file.

For UTF-8 and UTF, you need to parse the data manually since a single character can be represented by a variable number of bytes. Also, if you're really anal, you'll want to use the locale variant of iswprint if that's available on your platform.

Perl has a decent heuristic. Use the -B operator to test for binary and its opposite, -T to test for text. Here's shell a one-liner to list text files:. Its an old topic, but maybe someone will find this useful. If you have to decide in a script if something is a file then you can simply do like this :. You can use libmagic which is a library version of the Unix file command line. Most programs that try to tell the difference use a heuristic, such as examining the first n bytes of the file and seeing if those bytes all qualify as 'text' or not i.

For finer distiction there's always the 'file' command on UNIX-like systems. This command uses a configuration file that defines magic numbers contained within many popular file structures.

The magic file defines offsets of values known to exist within the file and can then examine these locations to determine the type of the file.

The structure and description of the magic file can be found by consulting the relevant manual page man magic.

As for an implementation, well that can be found within file. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

The output is not likely to be useful. But, as Mark Ransom said, that would be generally not wise on compressed files; the exception is "synchronizable" compressed formats like that produced by gzip --rsyncable , in which small differences in the uncompressed files should have a limited effect on the compressed file. Show 4 more comments. Command explanation: -An removes the address column. It is crucial to have one byte per line, or else every line after a deletion would become out of phase and differ.

The good side of this method is that od is extremely powerful. In particular, it lets one compare longer-than-a-byte objects, e. Add a comment. Evgeny Evgeny 1 1 gold badge 8 8 silver badges 11 11 bronze badges.

Of course, one may use diff instead of vimdiff. I'd recommend hexdump for dumping binary files to textual format and kdiff3 for diff viewing. BugoK BugoK 1 1 silver badge 4 4 bronze badges. Can you add something to this answer about its properties without "Edit:", "Update:", or similar? The hexdiff is a program designed to do exactly what you're looking for.

Usage: hexdiff file1 file2 It displays the hex and 7-bit ASCII of the two files one above the other, with any differences highlighted. Mick Mick 2 2 silver badges 1 1 bronze badge. But it does a pretty bad job when it comes to the comparing part. If you insert some bytes into a file, it will mark all byte afterwards as changes — Murmel. Murmel while I agree, isn't that what's being asked here?

EvanCarroll true, and hence I left a comment only and did not downvote — Murmel. I also didn't down vote Mick, but I agree with you and answered here superuser. Peter Mortensen John Lawrence Aspden John Lawrence Aspden 2 2 gold badges 12 12 silver badges 21 21 bronze badges.

Vincent Vega Vincent Vega 11 1 1 bronze badge. Welcome to SuperUser! Although this software looks like it could solve the OP's problem, pure advertisement is strongly frowned upon on the Stack Exchange network. If you are affiliated to this software's editor, please disclose this fact. And try to rewrite your post so that it looks less like a commercial. Eilisha Shiraini. I am not affiliated with dhex in any way. I copied the author's description into the post because there is minimum post length limit — Vincent Vega.

Already mentioned at: superuser. There is already an answer about DHEX. It displays results side by side with colors, and this greatly facilitate analysis. PL : A side-by-side visual diff for binary files. Consult usage subroutine below for help. Copyright C Jerome Lelasseux jl jjazzlab. Show byte modifications but also additions and deletions, whatever the number of changed bytes.

Rely on the 'diff' external command such as found on Linux or Cygwin. The algorithm is not suited for large and very different files. Needed if you view the output in an editor.

Community Bot 1. Can it be used on arbitrary binary files, though? That page seems to indicate that it's only useful for comparing executables that have been disassembled by Hex-Rays IDA Pro. See also: Radare's radiff2 for binary diffing.

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