6 2. Differences from standard XZ Utils
7 3. LZMA Utils compatibility
13 XZ Utils should have been called LZMA Utils 4.42, but it came too late.
14 The old .lzma file format has some problems, worst of which is the lack
15 of magic number, but it gets enough use to still need to be supported.
16 See /usr/share/doc/xz-utils/history.txt.gz for the full story.
18 Differences from standard XZ Utils
19 ----------------------------------
21 XZ Utils 5.1.y has some experimental features which are disabled in
22 Debian to allow interfaces to evolve. Debian liblzma is also modified
23 to avoid breakage when the same process loads liblzma2 from Debian 6.0
24 (squeeze) and liblzma5.
27 Disable threaded compression in liblzma and xz.
30 liblzma: Do not pretend to satisfy dependencies on XZ_5.1.1alpha.
32 abi-liblzma2-compat, configure-liblzma2-compat
33 Do not check reserved fields past the historical end of the
34 lzma_stream structure if liblzma.so.2 is loaded in the same
35 process image. Likewise when linked statically.
38 man-date, man-xz-lvv-minver (from upstream)
39 Document the "Minimum version required to decompress" field of
40 "xz --robot -v -v --list" output.
42 xz-lvv-empty-block-minver (from upstream)
43 Fix the version number printed by "xz -lvv" for files with Blocks
44 of zero uncompressed_size: the decoder bug preventing reading such
45 files was fixed in xz 5.0.2, not 5.0.3.
47 decoder-check-first-0x00 (from upstream)
48 Check that the first byte of range encoded data is zero to catch
51 Changes in 5.1.2alpha not applied:
53 Docs: Language fix to 01_compress_easy.c
54 xz: Add incomplete support for --block-list
55 INSTALL: Document --enable-symbol-versions
56 configure: Add a comment about *-linux tuples for clarity
57 TODO: Warn that threads and fork() do not mix well
58 Bump the version number and update NEWS for 5.1.2alpha
60 LZMA Utils compatibility
61 ------------------------
63 To support old scripts and muscle memory, XZ Utils can emulate the
64 legacy LZMA Utils interface. To use this feature, you can install some
65 subset of the following list of symbolic links to your $PATH.
67 lzma, unlzma, lzcat -> /usr/bin/xz
68 lzgrep, lzegrep, lzfgrep -> /usr/bin/xzgrep
69 lzless -> /usr/bin/xzless
70 lzmore -> /usr/bin/xzmore
71 lzdiff, lzcmp -> /usr/bin/xzdiff
73 If you would like XZ Utils to provide these commands by default for
74 all users, use "update-alternatives --config lzma".
79 The memory usage of xz can vary from a few hundred kilobytes to several
80 gigabytes depending on the compression settings. If you would like xz
81 to automatically scale down its settings while compressing to decrease
82 memory usage, you can declare so by adding an option like the
83 following to your environment (e.g., in ~/.profile):
85 XZ_DEFAULTS=--memlimit-compress=256MiB
88 See the "Memory usage" section of the xz(1) manual page for details.
90 -- Jonathan Nieder <jrnieder@gmail.com> Mon, 10 Sep 2012 14:35:27 -0700