diff a gzipped tarball against a directory?

Question

Is there a way I can diff a gzipped tarball against an existing directory?

I would like to be able to do it without extracting the data from the tarball.

Answer 1

Mount the tarball as a directory, for example with AVFS. Then use diff -r on the real directory and the point where the tarball is mounted.

mountavfs
diff -r ~/.avfs/path/to/foo.tar.gz\# real-directory

Answer 2

Turns out that GNU tar has diff built in (-d):

$ #Create the archive and a difference:
$ echo one>file1;echo two>file2;tar -czf archive.tgz file*;echo changing>>file1
$ tar -dzf archive.tgz
file1: Size differs

If you are working with tar that does not have this try:

$ for F in `tar -tzf archive.tgz`;do tar -xzOf archive.tgz $F|diff --brief - $F;done
Files - and file1 differ