2010-10-23 11:15:35 +00:00
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XZ Utils User-Visible Changes
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=============================
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5.0.0 (2010-10-23)
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Only the most important changes compared to 4.999.9beta are listed
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here. One change is especially important:
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* The memory usage limit is now disabled by default. Some scripts
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written before this change may have used --memory=max on xz command
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line or in XZ_OPT. THESE USES OF --memory=max SHOULD BE REMOVED
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NOW, because they interfere with user's ability to set the memory
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usage limit himself. If user-specified limit causes problems to
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your script, blame the user.
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Other significant changes:
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* Added support for XZ_DEFAULTS environment variable. This variable
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allows users to set default options for xz, e.g. default memory
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usage limit or default compression level. Scripts that use xz
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must never set or unset XZ_DEFAULTS. Scripts should use XZ_OPT
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instead if they need a way to pass options to xz via an
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environment variable.
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* The compression settings associated with the preset levels
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-0 ... -9 have been changed. --extreme was changed a little too.
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It is now less likely to make compression worse, but with some
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files the new --extreme may compress slightly worse than the old
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--extreme.
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* If a preset level (-0 ... -9) is specified after a custom filter
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chain options have been used (e.g. --lzma2), the custom filter
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chain will be forgotten. Earlier the preset options were
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completely ignored after custom filter chain options had been
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seen.
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* xz will create sparse files when decompressing if the uncompressed
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data contains long sequences of binary zeros. This is done even
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when writing to standard output that is connected to a regular
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file and certain additional conditions are met to make it safe.
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* Support for "xz --list" was added. Combine with --verbose or
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--verbose --verbose (-vv) for detailed output.
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* I had hoped that liblzma API would have been stable after
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4.999.9beta, but there have been a couple of changes in the
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advanced features, which don't affect most applications:
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- Index handling code was revised. If you were using the old
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API, you will get a compiler error (so it's easy to notice).
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- A subtle but important change was made to the Block handling
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API. lzma_block.version has to be initialized even for
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lzma_block_header_decode(). Code that doesn't do it will work
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for now, but might break in the future, which makes this API
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change easy to miss.
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* The major soname has been bumped to 5.0.0. liblzma API and ABI
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are now stable, so the need to recompile programs linking against
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liblzma shouldn't arise soon.
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