XZ
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'''XZ''' is a stream compression format with built-in integrity checks. It uses [[LZMA2]] compression. Compressed streams are able to be concatenated and still be decompressible like a single-stream file. | '''XZ''' is a stream compression format with built-in integrity checks. It uses [[LZMA2]] compression. Compressed streams are able to be concatenated and still be decompressible like a single-stream file. | ||
| − | XZ is a successor to [[LZMA Alone|LZMA_Alone]] format, and an alternative to [[Lzip]]. The compression format is offered as an option among the likes of [[vmlinuz]]<ref>[https://github.com/torvalds/linux/blob/master/scripts/extract-vmlinux#L52 extract-vmlinux shell script (line 52) - Linus Torvalds' kernel - GitHub]</ref>, [[initramfs]]<ref>[https://github.com/dracut-ng/dracut-ng/blob/main/man/dracut.conf.5.adoc?plain=1#L119-L123 dracut.conf.5.adoc - dracut-ng manual pages - GitHub]</ref><ref>[https://gitlab.archlinux.org/archlinux/mkinitcpio/mkinitcpio/-/blob/master/mkinitcpio.conf?ref_type=heads#L61-67 mkinitcpio.conf (lines 61-67) - mkinitcpio - Arch Linux GitLab]</ref><ref>[https://github.com/anatol/booster/blob/master/docs/manpage.md?plain=1#L57 manpage.md (line 57) - booster - GitHub]</ref>, [[SquashFS|<code>squashfs-tools</code>]]<ref>[https://github.com/plougher/squashfs-tools/blob/master/squashfs-tools/compressor.c#L31-L77 compressor.c (lines 31-77) - squashfs-tools - GitHub]</ref> and finally as a specific switch <code>-J</code> or <code>--xz</code> in GNU [[tar]]<ref>[https://www.gnu.org/software/tar/manual/tar.html#gzip | + | XZ is a successor to [[LZMA Alone|LZMA_Alone]] format, and an alternative to [[Lzip]]. The compression format is offered as an option among the likes of [[vmlinuz]]<ref>[https://github.com/torvalds/linux/blob/master/scripts/extract-vmlinux#L52 extract-vmlinux shell script (line 52) - Linus Torvalds' kernel - GitHub]</ref>, [[initramfs]]<ref>[https://github.com/dracut-ng/dracut-ng/blob/main/man/dracut.conf.5.adoc?plain=1#L119-L123 dracut.conf.5.adoc - dracut-ng manual pages - GitHub]</ref><ref>[https://gitlab.archlinux.org/archlinux/mkinitcpio/mkinitcpio/-/blob/master/mkinitcpio.conf?ref_type=heads#L61-67 mkinitcpio.conf (lines 61-67) - mkinitcpio - Arch Linux GitLab]</ref><ref>[https://github.com/anatol/booster/blob/master/docs/manpage.md?plain=1#L57 manpage.md (line 57) - booster - GitHub]</ref>, [[SquashFS|<code>squashfs-tools</code>]]<ref>[https://github.com/plougher/squashfs-tools/blob/master/squashfs-tools/compressor.c#L31-L77 compressor.c (lines 31-77) - squashfs-tools - GitHub]</ref> and finally as a specific switch <code>-J</code> or <code>--xz</code> in GNU [[tar]]<ref>[https://www.gnu.org/software/tar/manual/tar.html#gzip 8.1.1 Creating and Reading Compressed Archives - GNU tar 1.35 online manual (single page) - gnu.org]</ref> under [[Linux]]. |
== Identification == | == Identification == | ||
Revision as of 08:13, 16 August 2025
XZ is a stream compression format with built-in integrity checks. It uses LZMA2 compression. Compressed streams are able to be concatenated and still be decompressible like a single-stream file.
XZ is a successor to LZMA_Alone format, and an alternative to Lzip. The compression format is offered as an option among the likes of vmlinuz[2], initramfs[3][4][5], squashfs-tools[6] and finally as a specific switch -J or --xz in GNU tar[7] under Linux.
Contents |
Identification
XZ files always have lengths that are multiples of 4 bytes, and they begin with a 6-byte "magic" sequence of (hex) FD 37 7A 58 5A 00 and end with footer "magic bytes" of 59 5A. (The ending bytes can be verified as a sign that the file has not been truncated in transmission.)
Software
- 7-Zip
- LZMA SDK
- XZ Utils:
-
xz,unxz,xzcat, etc. -
xzdec - liblzma
-
- XZ Embedded
Sample files
- dexvert samples — archive/xz
- Search results of files with .xz extension, belongs to archive family and is the format xz - Discmaster.textfiles.com
Links
- Current spec
- Official site (has historical specs with other info)
- Wikipedia article
- Xz format inadequate for long-term archiving - Analysis of weaknesses and design errors in the xz format, by the author of another format
References
- ↑ The .xz File Format - Version 1.0.0 (2009-01-14) - tukaani.org
- ↑ extract-vmlinux shell script (line 52) - Linus Torvalds' kernel - GitHub
- ↑ dracut.conf.5.adoc - dracut-ng manual pages - GitHub
- ↑ mkinitcpio.conf (lines 61-67) - mkinitcpio - Arch Linux GitLab
- ↑ manpage.md (line 57) - booster - GitHub
- ↑ compressor.c (lines 31-77) - squashfs-tools - GitHub
- ↑ 8.1.1 Creating and Reading Compressed Archives - GNU tar 1.35 online manual (single page) - gnu.org
