When generating an ISO image using the genisoimage command (apparently "a carbon copy of mkisofs"):

genisoimage -o image.iso path/to/source/directory

Is a checksum or other type of verification done by this command to ensure that the ISO contents exactly match the contents of the source directory?

I'm currently checking the success of this operation by looking at the exit code, but I have a concern about a theoretical rare case where (even if only in extreme situations such as old/failing hard drives) the command completes with an exit code of 0, but the contents of the generated image do not exactly match the contents of the source directory.

  • genisoimage is based in the mkisofs sources from 2004. To make it unique, plenty of bugs have been added while the original program fixed plenty of bugs, added a lot of new functionality and enhanced the performance. My advise is to use a recent original and if you are not sure, call mkisofs -version and check whether there is a Copyright Jörg Shilling inside the output. – schily Jul 9 '18 at 11:03

It doesn't, and there's not much point in it doing so: a checksum is only useful if it provides independent verification. In this case, you'd effectively be checking the result of two successive reads of the same files; if you can't trust your storage to produce the same result twice, which reads are you going to trust to produce your image?

If you want to verify a generated image, you should extract it (e.g. using 7z) and compare the extracted files with the originals.

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