Re: [Bug-tar] Re: AMTAR brokenness

[Sergey Poznyakoff]

Alexandre Duret-Lutz <address@hidden> wrote:

> On second though, shouldn't we try to use pax first?  tar is no
> longer a POSIX requirement, right?

Right, but I'd say it's too early to relay on pax.
 
> Also do we really need to try `-o'?

No, we do not.

> Besides GNU tar, is there some tar implementation that does not
> default to the ustar format?

GNU tar 1.14 will be the last release that uses non-portable GNU format
by default. Subsequent versions will default to 'ustar' format.
 
> How about this scheme:
> 
>   Use `pax -x ustar' if it works.
> 
>   Otherwise try `tar --format=ustar'.

This looks OK (though see my comment above).

>   Otherwise use `POSIXLY_CORRECT=1 tar'.  (I'm assuming that
>   POSIXLY_CORRECT=1 will coerce older tar versions into 
>   producing ustar format.  Am I wrong, or is there another 
>   way?)

No, it will not. Previous versions of GNU tar were not able to produce
correct 'ustar' archives. Whatever options you give to previous versions
of GNU tar, the produced archives will deviate from the standard.
Using -o does not help much, either: if the file list to be archived
contains long filenames or symbolic links, tar will create GNU extension
headers for them, thus hurting the portability of the resulting archive.

Regards,
Sergey