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`--compress' (`-Z') indicates an archive stored in compressed format.
The `--compress' (`-Z') option is useful in saving time over networks and
space in pipes, and when storage space is at a premium.
`--compress' (`-Z') causes tar to compress when writing the
archive, or to uncompress when reading the archive.
To perform compression and uncompression on the archive, tar
runs the compress utility. tar uses the default
compression parameters; if you need to override them, avoid the
`--compress' (`-Z') option and run the compress utility
explicitly. It is useful to be able to call the compress
utility from within tar because the compress utility by
itself cannot access remote tape drives.
The `--compress' (`-Z') option will not work in conjunction with the `--multi-volume' (`-M') option or the `--append' (`-r'), `--update' (`-u'), `--append' (`-r') and `--delete' operations.
FIXME: xref Modifying, for more information on these operations.
If there is no compress utility available, tar will report an
error.
`--compress-blocks' is like `--compress' (`-Z'), but when used in
conjunction with `--create' (`-c') also causes tar to pad the last
block of the archive out to the next block boundary as it is written.
This is useful with certain devices which require all write operations
be a multiple of a specific size.
Please Note: The compress program may be covered by a patent,
and therefore we recommend you stop using it. We hope to have a
different compress program in the future. We may change the name of
this option at that time.
tar will compress (when writing
an archive), or uncompress (when reading an archive). Used in
conjunction with the `--create' (`-c'), `--extract' (`-x'), `--list' (`-t') and
`--compare' (`-d') operations.
FIXME: why not use -Z instead of -z -z ?
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