| XZ Utils for Debian |
| =================== |
| |
| Contents: |
| 1. History |
| 2. Differences from standard XZ Utils |
| 3. LZMA Utils compatibility |
| 4. Configuration |
| |
| History |
| ------- |
| |
| XZ Utils should have been called LZMA Utils 4.42, but it came too late. |
| The old .lzma file format has some problems, worst of which is the lack |
| of magic number, but it gets enough use to still need to be supported. |
| See /usr/share/doc/xz-utils/history.txt.gz for the full story. |
| |
| Differences from standard XZ Utils |
| ---------------------------------- |
| |
| XZ Utils 5.1.y has some experimental features which are disabled in |
| Debian to allow interfaces to evolve. Debian liblzma is also modified |
| to avoid breakage when the same process loads liblzma2 from Debian 6.0 |
| (squeeze) and liblzma5. |
| |
| abi-threaded-encoder |
| Disable threaded compression in liblzma and xz. |
| |
| abi-version-script |
| liblzma: Do not pretend to satisfy dependencies on XZ_5.1.1alpha. |
| |
| abi-liblzma2-compat, configure-liblzma2-compat |
| Do not check reserved fields past the historical end of the |
| lzma_stream structure if liblzma.so.2 is loaded in the same |
| process image. Likewise when linked statically. |
| (See bug #649522.) |
| |
| man-date, man-xz-lvv-minver (from upstream) |
| Document the "Minimum version required to decompress" field of |
| "xz --robot -v -v --list" output. |
| |
| xz-lvv-empty-block-minver (from upstream) |
| Fix the version number printed by "xz -lvv" for files with Blocks |
| of zero uncompressed_size: the decoder bug preventing reading such |
| files was fixed in xz 5.0.2, not 5.0.3. |
| |
| decoder-check-first-0x00 (from upstream) |
| Check that the first byte of range encoded data is zero to catch |
| broken files sooner. |
| |
| Changes in 5.1.2alpha not applied: |
| |
| Docs: Language fix to 01_compress_easy.c |
| xz: Add incomplete support for --block-list |
| INSTALL: Document --enable-symbol-versions |
| configure: Add a comment about *-linux tuples for clarity |
| TODO: Warn that threads and fork() do not mix well |
| Bump the version number and update NEWS for 5.1.2alpha |
| |
| LZMA Utils compatibility |
| ------------------------ |
| |
| To support old scripts and muscle memory, XZ Utils can emulate the |
| legacy LZMA Utils interface. To use this feature, you can install some |
| subset of the following list of symbolic links to your $PATH. |
| |
| lzma, unlzma, lzcat -> /usr/bin/xz |
| lzgrep, lzegrep, lzfgrep -> /usr/bin/xzgrep |
| lzless -> /usr/bin/xzless |
| lzmore -> /usr/bin/xzmore |
| lzdiff, lzcmp -> /usr/bin/xzdiff |
| |
| If you would like XZ Utils to provide these commands by default for |
| all users, use "update-alternatives --config lzma". |
| |
| Configuration |
| ------------- |
| |
| The memory usage of xz can vary from a few hundred kilobytes to several |
| gigabytes depending on the compression settings. If you would like xz |
| to automatically scale down its settings while compressing to decrease |
| memory usage, you can declare so by adding an option like the |
| following to your environment (e.g., in ~/.profile): |
| |
| XZ_DEFAULTS=--memlimit-compress=256MiB |
| export XZ_DEFAULTS |
| |
| See the "Memory usage" section of the xz(1) manual page for details. |
| |
| -- Jonathan Nieder <jrnieder@gmail.com> Mon, 10 Sep 2012 14:35:27 -0700 |