How to compare two tarball's content

Question

I want to tell whether two tarball files contain identical files, in terms of file name and file content, not including meta-data like date, user, group.

However, There are some restrictions: first, I have no control of whether the meta-data is included when making the tar file, actually, the tar file always contains meta-data, so directly diff the two tar files doesn't work. Second, since some tar files are so large that I cannot afford to untar them in to a temp directory and diff the contained files one by one. (I know if I can untar file1.tar into file1/, I can compare them by invoking 'tar -dvf file2.tar' in file/. But usually I cannot afford untar even one of them)

Any idea how I can compare the two tar files? It would be better if it can be accomplished within SHELL scripts. Alternatively, is there any way to get each sub-file's checksum without actually untar a tarball?

Thanks,

Answer 1

Try also pkgdiff to visualize differences between packages (detects added/removed/renamed files and changed content, exist with zero code if unchanged):

pkgdiff PKG-0.tgz PKG-1.tgz