Hi Chris, > The man page section on sparse files[1] suggests that the "old GNU > format" is risky, as it violates POSIX. As such, I was expecting to use > tar --sparse-version=1.0 to get better behaviour, or for that to be the > default for --sparse. > > However, for the default of --format=gnu, --sparse-version=1.0 is
The only sparse format that can be used when creating legacy gnu archives is "Old GNU" [1]. Both 0.1 [2] and 1.0 [3] formats can be used only with archives in pax format. In fact, the --sparse-version option is silently ignored when used with --format=gnu. Arguably it would be better to just bail out in that case. I'm not quite sure. > I note that the pax format embeds the current pid[2] into[3] the tar > file, apparently as a source of a "unique" random number, which seems That's what mandated by the standard [4]: "If no -o exthdr.name= string is specified, pax shall use the following default value: %d/PaxHeaders.%p/%f" You can use the --pax-option (analogous to the pax -o option), as suggested above, if that doesn't suit your needs. Best regards, Sergey [1] http://www.gnu.org/software/tar/manual/html_node/Old-GNU-Format.html [2] http://www.gnu.org/software/tar/manual/html_node/PAX-0.html [3] http://www.gnu.org/software/tar/manual/html_node/PAX-1.html [4] http://pubs.opengroup.org/onlinepubs/009695399/utilities/pax.html
