Error with option --strip-components when running example from manual of tar command

Question

When reading the manual of tar command I encountered something wrong with the option --strip-components. The example in the manual is that there is a tar file containing a directory with 3 files. When listed with the tar command it looks like this:

$tar -tf music.tar
practice/
practice/blues
practice/folk
practice/jazz

The manual says the --strip-components option

allow you to strip away a certain number of leading directory components

and

tar --extract --file=music.tar --strip-components=1 folk

will extract the file ‘folk’ into the current working directory.

But when I run this command on Ubuntu, I got this error

tar: folk: Not found in archive
tar: Exiting with failure status due to previous errors

And my tar version is 1.34. Besides, I got file folk extracted successfully when I executed the command below

tar --extract --file=music.tar --strip-components=1 practice/folk

Did I have some misunderstanding about the manual and option --strip-components? Or is there something wrong with the manual?

Answer 1

That particular example is wrong - you still need to specify the full path of the file inside the archive. Otherwise, given a tar file like:

$ tar -tf foo.tar
a/
a/folk
b/folk
b/blues

There would be no way for tar to tell which file you meant with tar --extract --file=foo.tar --strip-components=1 folk.

The section documenting --strip-components (6.7 Modifying File and Member Names) has a correct example:

For example, suppose you have archived whole ‘/usr’ hierarchy to a tar archive named ‘usr.tar’. Among other files, this archive contains ‘usr/include/stdlib.h’, which you wish to extract to the current working directory. To do so, you type:

$ tar -xf usr.tar --strip=2 usr/include/stdlib.h

The option ‘--strip=2’ instructs tar to strip the two leading components (‘usr/’ and ‘include/’) off the file name.

If you add the ‘--verbose’ (‘-v’) option to the invocation above, you will note that the verbose listing still contains the full file name, with the two removed components still in place.