Friday, October 2, 2009

XZ takes over Gzip in RPM

As per the Fedora 12 Feature List, RPM packages will be compressed with xz instead of gzip, making the iso reduce by 30% in size, and 15% smaller compared to the bzip2 compression which is also an option, though bzip2 adds greater compression, but all this goes at the cost of large memory and cpu time. XZ on the other hand allows better compression without any of these.Thanks to Tukaani, the developer channel [presently one man army] behind the making of XZ Utils.

The core of the XZ Utils compression code is based on LZMA SDK, which is still in rapid development and hence Fedora will just using XZ instead of the not-finalized LZMA.

XZ Utils consist of several components:
- liblzma is a compression library with API similar to that of zlib.
- xz is a command line tool with syntax similar to that of gzip.
- xzdec is a decompression-only tool smaller than the full-featured xz tool.
- A set of shell scripts (xzgrep, xzdiff, etc.) have been adapted from gzip to ease viewing, grepping, and comparing compressed files.
- Emulation of command line tools of LZMA Utils eases transition from LZMA Utils to XZ Utils.

RPM [rpm-4.7.1-1] will be capable of compressing using xz.

Sources :
- XZRpmPayloads
- XZ Utils


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