tar: old

1 
1 8.3.4 Old V7 Archives
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1 
1 Certain old versions of 'tar' cannot handle additional information
1 recorded by newer 'tar' programs.  To create an archive in V7 format
1 (not ANSI), which can be read by these old versions, specify the
1 '--format=v7' option in conjunction with the '--create' ('-c') ('tar'
1 also accepts '--portability' or '--old-archive' for this option).  When
1 you specify it, 'tar' leaves out information about directories, pipes,
1 fifos, contiguous files, and device files, and specifies file ownership
1 by group and user IDs instead of group and user names.
1 
1    When updating an archive, do not use '--format=v7' unless the archive
1 was created using this option.
1 
1    In most cases, a _new_ format archive can be read by an _old_ 'tar'
1 program without serious trouble, so this option should seldom be needed.
1 On the other hand, most modern 'tar's are able to read old format
1 archives, so it might be safer for you to always use '--format=v7' for
1 your distributions.  Notice, however, that 'ustar' format is a better
1 alternative, as it is free from many of 'v7''s drawbacks.
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