Convert 7Z to TXZ

Why Convert 7Z to TXZ?

Converting 7Z to TXZ (tar.xz) gives you the best of both worlds: LZMA2 compression ratios virtually identical to 7Z combined with TAR's full Unix metadata preservation. The resulting archive maintains file permissions, user/group ownership, symbolic links, and device nodes — all metadata that 7Z cannot store. For Linux software distribution, TXZ is the gold standard format.

TXZ is the official distribution format for the Linux kernel (kernel.org), GNU project tools, and the majority of major open-source projects. Package managers like dpkg (Debian/Ubuntu) and rpm (Fedora/RHEL) use XZ compression natively. Converting 7Z to TXZ aligns your archives with this established ecosystem and ensures they are accepted by all Linux distribution packaging workflows.

Unlike 7Z, XZ provides native multi-threaded compression (xz -T0) that is deeply integrated with Linux system tools. The 'tar -cJf' command automatically invokes XZ, and environment variables like XZ_OPT allow global configuration of threading and compression levels. This seamless integration makes TXZ far more practical for automated Linux build and packaging workflows.

TXZ supports BCJ (Branch/Call/Jump) pre-filters that optimize compression of executable code. When archiving compiled binaries, shared libraries, or kernel modules, BCJ filters can reduce the archive size by an additional 5-10% compared to standard LZMA2 — a capability unique to the XZ implementation that 7Z's LZMA2 does not apply by default.

Key Benefits of Converting 7Z to TXZ:

• Same Compression: LZMA2 produces virtually identical file sizes to 7Z
• Unix Metadata: Preserves permissions, ownership, symlinks — impossible in 7Z
• Linux Standard: Official format for Linux kernel and GNU project releases
• Package Compatible: dpkg, RPM, and Portage handle tar.xz natively
• Multi-threaded: Native parallel compression with xz -T0
• BCJ Filters: Improved compression for executable binaries
• Build System Ready: Works with autotools, CMake, Meson, and all build systems

Practical Examples

Example 1: Creating an Official Linux Kernel Module Release

Scenario: A kernel developer needs to convert an out-of-tree driver module from 7Z to the standard tar.xz format matching kernel.org conventions.

Source: wifi-driver-v5.2.7z (12 MB, kernel module source)
Conversion: 7Z → TXZ
Result: wifi-driver-v5.2.tar.xz (12.1 MB)

Release:
✓ Matches kernel.org's linux-x.y.z.tar.xz format
✓ DKMS and kmod tools expect standard tar archives
✓ Makefile executable permissions preserved
✓ BCJ filter applied to compiled test binaries
✓ Multi-threaded extraction on build servers

Example 2: Preparing Debian Package Source

Scenario: A Debian maintainer needs the upstream source in .orig.tar.xz format for the Debian packaging process.

Source: myapp-2.0.7z (35 MB, application source)
Conversion: 7Z → TXZ
Result: myapp_2.0.0.orig.tar.xz (35.5 MB)

Debian packaging:
✓ dpkg-source -b requires .orig.tar.{gz,bz2,xz}
✓ Debian Policy recommends xz for best compression
✓ debuild, pbuilder, and sbuild handle tar.xz natively
✓ Launchpad PPA accepts .orig.tar.xz uploads
✓ Less mirror bandwidth than .orig.tar.gz

Example 3: Fedora RPM Spec File Source Archive

Scenario: A Fedora package maintainer needs to convert a 7Z source archive for use in an RPM .spec file.

Source: libwidget-1.8.7z (8 MB, C library)
Conversion: 7Z → TXZ
Result: libwidget-1.8.0.tar.xz (8.2 MB)

RPM workflow:
✓ Source0: in .spec file points to .tar.xz
✓ rpmbuild %setup macro handles tar.xz automatically
✓ Mock and Koji build systems support tar.xz
✓ Fedora packaging guidelines prefer xz compression
✓ Copr build service accepts tar.xz sources

Frequently Asked Questions (FAQ)

Q: Is the file size different between 7Z and TXZ?

A: Nearly identical. Both use LZMA2 compression. The TXZ file may be 1-3% larger due to TAR metadata overhead (storing permissions, ownership, timestamps for each file). For practical purposes, the compression is equivalent.

Q: Why is TXZ preferred over 7Z on Linux?

A: TXZ preserves Unix metadata (permissions, symlinks) that 7Z cannot store. It is the standard for the Linux kernel, GNU, Debian, Fedora, and Arch. XZ tools are pre-installed everywhere. The tar+xz combination integrates with all build systems and package managers natively.

Q: Does TXZ support encryption?

A: No. Neither TAR nor XZ provides built-in encryption. If you need encrypted archives, use GPG on the TXZ file or keep the 7Z format. For pure compression and archiving, TXZ is the superior Linux-native format.

Q: Can TXZ handle 7Z's solid compression advantage?

A: Yes, effectively. TAR concatenates all files into one stream, and XZ compresses that single stream with LZMA2. This is essentially the same as 7Z solid compression — patterns found in earlier files benefit the compression of later files.

Q: Is multi-threaded extraction supported?

A: Yes. XZ supports multi-threaded decompression when the archive contains multiple blocks. The xz -T0 flag enables automatic parallel processing. Modern xz versions (5.4+) handle multi-threaded decompression efficiently.

Q: What are BCJ filters and how do they help?

A: BCJ (Branch/Call/Jump) filters pre-process executable machine code before LZMA2 compression, converting relative addresses to absolute ones. This creates more redundancy that LZMA2 can exploit, improving compression of binaries by 5-10%.

Q: Is there data loss when converting?

A: No. Both formats use lossless LZMA2 compression. The conversion decompresses all data from 7Z and repackages it in TAR format compressed with XZ. File contents are bit-for-bit identical.

Q: Which is better — TXZ or TGZ?

A: TXZ (tar.xz) gives the best compression, similar to 7Z. TGZ (tar.gz) decompresses 3-5x faster. Use TXZ for releases and distribution (minimize download size). Use TGZ for CI/CD and Docker (minimize extraction time). Many projects offer both.