Suppose I had a RAR archive split in several smaller files and the names of the resulting files have later on been changed.

Is there any way to determine the correct order of files?

5 Answers 5


Open any filepart in winrar, then get the information of the file (Alt+I).

No matter what the file name is, it will show you the order of file (volume 1, volume 2...). Rename the file parts as it was shown.


You can get the volume number with unrar, given that the info is present in the archive header:

unrar l myarchive.rar

The volume shows up in the lower right corner of the output:

0                0 101753210   0%       volume 118

To specify a password, use the following:

unrar l -pmypassword myarchive.rar


I have found the specification of the rar headers, it does not mention multipart explicity but it looks like it is covered by it.

Looking at the 'archive' headers, there are not fields that show the order of the file. Of course, that specification is incomplete (there are even two reserved fields), but I found nothing better in the web.

Here is the source coude to unrar, from there you should be able to know if there is such thing. But if you are able to check this, probably it will be easier to just write a program to try all permutations of the files and check with the unrar DLL if it works or not...

So, my answer is "if it is possible at all, it is complicated to find out". My bet would be contacting [email protected] and hope for the best

  • Looks interesting! If I don't manage to decode the format, I'll probably end up writing shell script to try everything out.
    – AndrejaKo
    Nov 19, 2011 at 20:25

Late answer, but that may be useful to future reference. There is an optional volume number field in the Main archive header, as specified here: http://www.rarlab.com/technote.htm

Most of the time this field is present, but there is no guarantee. For example you see more and more often renumbered RAR archives on usenet posts, this is obviously coming with this field to re-organize the volumes, or sometimes with a text file containing the sequence and another way to identify the corresponding files (like a CRC-32).


Late answer but a google search brought me here, so maybe others too. I just took a look myself and it looks like the last byte after all the data and before the few padding zeros at the end of the file, is the volume index (starting with 00). And 7zip shows the volume index too, when you click on "properties".

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