1 2XZ Utils User-Visible Changes 3============================= 4 55.0.0 (2010-10-23) 6 7 Only the most important changes compared to 4.999.9beta are listed 8 here. One change is especially important: 9 10 * The memory usage limit is now disabled by default. Some scripts 11 written before this change may have used --memory=max on xz command 12 line or in XZ_OPT. THESE USES OF --memory=max SHOULD BE REMOVED 13 NOW, because they interfere with user's ability to set the memory 14 usage limit himself. If user-specified limit causes problems to 15 your script, blame the user. 16 17 Other significant changes: 18 19 * Added support for XZ_DEFAULTS environment variable. This variable 20 allows users to set default options for xz, e.g. default memory 21 usage limit or default compression level. Scripts that use xz 22 must never set or unset XZ_DEFAULTS. Scripts should use XZ_OPT 23 instead if they need a way to pass options to xz via an 24 environment variable. 25 26 * The compression settings associated with the preset levels 27 -0 ... -9 have been changed. --extreme was changed a little too. 28 It is now less likely to make compression worse, but with some 29 files the new --extreme may compress slightly worse than the old 30 --extreme. 31 32 * If a preset level (-0 ... -9) is specified after a custom filter 33 chain options have been used (e.g. --lzma2), the custom filter 34 chain will be forgotten. Earlier the preset options were 35 completely ignored after custom filter chain options had been 36 seen. 37 38 * xz will create sparse files when decompressing if the uncompressed 39 data contains long sequences of binary zeros. This is done even 40 when writing to standard output that is connected to a regular 41 file and certain additional conditions are met to make it safe. 42 43 * Support for "xz --list" was added. Combine with --verbose or 44 --verbose --verbose (-vv) for detailed output. 45 46 * I had hoped that liblzma API would have been stable after 47 4.999.9beta, but there have been a couple of changes in the 48 advanced features, which don't affect most applications: 49 50 - Index handling code was revised. If you were using the old 51 API, you will get a compiler error (so it's easy to notice). 52 53 - A subtle but important change was made to the Block handling 54 API. lzma_block.version has to be initialized even for 55 lzma_block_header_decode(). Code that doesn't do it will work 56 for now, but might break in the future, which makes this API 57 change easy to miss. 58 59 * The major soname has been bumped to 5.0.0. liblzma API and ABI 60 are now stable, so the need to recompile programs linking against 61 liblzma shouldn't arise soon. 62 63