0

Is there an efficient way to verify a written tar-archive with transformed file names?

Assume I have a file called foo and want to store it in the archive as bar, I would create the archive foobar.tar like so:

$ tar -cf foobar.tar --transform="flags=r;s|foo|bar|" foo
$ tar --list -f foobar.tar 
bar

Now if I add the --verify option, this will result in an error:

$ tar --verify -cf foobar.tar --transform="flags=r;s|foo|bar|" foo
tar: Archive contains transformed file names.
tar: Verification may fail to locate original files.
tar: bar: Warning: Cannot stat: No such file or directory

I have unsuccessfully tried to fall-back on the --compare flag on the already created (and transformed) archive like-so,

$ tar --compare -f foobar.tar --transform="flags=r;s|foo|bar|" foo 
tar: foo: Not found in archive
tar: Exiting with failure status due to previous errors

but the --transform flag seems to be ignored. Another idea I had was to create the archive with original file names first, verify it during that step and then apply the transformation afterwards. However, I could not find any flag which tells tar to do in-situ transformations of file names. Here's an example using -u, which did not work (since -u only updates/appends given files).

$ tar --verify -f foobar.tar foo 
$ tar --transform="flags=r;s|foo|bar|" -uf foobar.tar
$ tar --list -f foobar.tar 
foo

I wish to write a program to manipulate the tar-headers manually or to implement my own verification routine. Anyhow, I would prefer sticking with standard UNIX tools. Furthermore, since I am working with very large archives, I want to avoid expensive operations such as generating temporary files.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.