Certain old versions of tar cannot handle additional
information recorded by newer tar programs. To create an
archive in V7 format (not ANSI), which can be read by these old
versions, specify the --format=v7 option in
conjunction with the --create (-c) (tar also
accepts --portability or ‘op-old-archive’ for this
option). When you specify it,
tar leaves out information about directories, pipes, fifos,
contiguous files, and device files, and specifies file ownership by
group and user IDs instead of group and user names.
When updating an archive, do not use --format=v7
unless the archive was created using this option.
In most cases, a new format archive can be read by an oldtar program without serious trouble, so this option should
seldom be needed. On the other hand, most modern tars are
able to read old format archives, so it might be safer for you to
always use --format=v7 for your distributions.
Published under the terms of the GNU General Public License