7Z to TXZ Converter

What is 7Z to TXZ Conversion?

Converting 7Z to TXZ is the transition to a modern Unix archive format that uses the same compression algorithm as 7Z itself. The TXZ extension is shorthand for tar.xz: data is first packed into a standard TAR container that preserves the directory hierarchy and POSIX metadata, after which the stream is compressed with the XZ utility. The XZ format was introduced in 2009 by a team of developers led by Lasse Collin and was designed as a successor to BZIP2 for the Unix community.

The key feature of TXZ is that its compressor XZ Utils uses the LZMA2 algorithm - the same one built into 7Z. This means that after conversion, the compression ratio will be very close to the source 7Z, typically differing by single digit percentages. The main gain is not in size but in native integration with Unix tooling: TXZ opens with tar xJf without installing third party packages, supports streaming through pipes, and correctly handles symlinks, permissions, and file owners.

In modern Linux distributions, the TXZ format has taken a dominant position. Linux kernel source archives on kernel.org are published in tar.xz. Debian and Ubuntu .deb packages and Fedora and RHEL .rpm packages internally use XZ compression for data. Many GNU projects have migrated from tar.bz2 to tar.xz due to better compression and comparable decompression speed.

Technical Differences Between 7Z and TXZ Formats

Compression Algorithms

Both formats use LZMA2 - a dictionary algorithm with range coding. This means the fundamental compression method is identical: searching for long repetitions in a large adaptive dictionary up to 1 GB, encoding the context model through arithmetic coding, optional preliminary filters (BCJ for executables, delta for media).

The main differences lie in:

• Container - 7Z uses its own archive format, TXZ uses TAR with an XZ wrapper.
• Solid mode - 7Z by default merges files into a single block for compression, which is more efficient for collections of similar documents. XZ works as a stream and has no concept of solid in the same sense.
• Encryption - 7Z supports AES-256 built in, the XZ standard has no encryption.
• Metadata - 7Z partially supports POSIX attributes, TAR provides full support.

Comparison Table

Real Compression Ratios

Since the algorithm is the same, the size difference between TXZ and 7Z is usually small:

TXZ may lose to 7Z on collections of very similar files due to the absence of solid mode in the full sense, but in most scenarios the difference stays within 5-10%.

When 7Z to TXZ Conversion is Necessary

Standard for Modern Linux Repositories

XZ has become the main compressor for the most important projects of the Unix world:

• Linux kernel - source archives linux-x.x.x.tar.xz are published on kernel.org as the main format since 2013.
• GNU projects - glibc, gcc, binutils, coreutils have moved to tar.xz for their releases.
• deb packages - modern .deb files for Debian and Ubuntu use XZ compression for data.tar inside.
• rpm packages - Fedora, RHEL, openSUSE apply XZ to the payload section of packages.
• Arch Linux - binary packages pkg.tar.xz and pkg.tar.zst are distributed through pacman.

If an archive is intended for long term storage in a Linux project repository, TXZ is the most expected format.

POSIX Attribute Preservation

Since TXZ is built on TAR, it inherits all the capabilities for working with Unix metadata:

• chmod permissions - file and directory modes are saved in octal form in each record header.
• UID/GID owners - user and group identifiers along with names are recorded in headers.
• Timestamps - mtime in each record, with PAX extensions adding atime, ctime, and nanosecond precision.
• Symlinks and hardlinks - preserved as references to target paths without duplicating content.
• Special files - block and character devices, FIFOs, and sockets are transferred as corresponding record types.
• Extended attributes - PAX extensions transfer xattr, ACL, SELinux labels.

Long Term Archival

For long term archives, TXZ has several advantages:

• Best compression in the Unix family - 10-30% more compact than BZIP2 with comparable decompression speed.
• Block checksums - the XZ format equips each block with CRC-32 or CRC-64, optionally SHA-256.
• Independent block extraction - in multi block XZ, data can be partially recovered from corruption.
• Open standardization - the XZ specification is published and maintained by the Tukaani Project consortium.
• Format stability - XZ has not changed its binary format since 2009, ensuring backward compatibility.

Transmission Through Unix Tools

TXZ integrates conveniently with typical Unix pipelines:

• Stream over ssh - the command tar cJf - dir | ssh host 'tar xJf - -C /path' transfers compressed data between servers without intermediate files.
• Parallel compression - the pxz utility and xz with the -T flag compress in multiple threads, accelerating processing on modern CPUs.
• Package managers - dpkg, rpm, pacman work with TXZ data natively when installing packages.
• Backup tools - bacula, amanda, restic support TXZ as one of the standard formats.

Conversion Process: What Happens to the Archive

Transformation Stages

1. Reading and decompressing 7Z - the source archive header is analyzed, LZMA2 blocks are decompressed into the original file bytes. For solid archives, the entire block is extracted at once.

2. File tree reconstruction - names, paths, and POSIX attributes are restored into a directory hierarchy with permissions, owners, and timestamps.

3. TAR stream formation - each file is preceded by a 512 byte header with metadata (name, size, permissions, owner, timestamps, record type, checksum), followed by content padded to a 512 byte boundary.

4. LZMA2 application - the TAR stream is split into blocks and passed through the LZMA2 compressor. The algorithm searches for repetitions in an adaptive dictionary up to 1 GB.

5. XZ wrapper - the compressed stream is preceded by an XZ stream header with magic number, flags, and checksum. After each block, a verification checksum is written (CRC-32 by default, optionally CRC-64 or SHA-256).

6. Finalization - at the end of the file, an XZ index with block boundaries is written for random access in some scenarios.

7. Saving - the result is written with the .tar.xz or .txz extension.

What is Preserved and What Changes

Preserved:

• File and directory names with full paths (including Unicode)
• Content of all files (byte for byte)
• Directory structure of any depth
• Modification timestamps
• Permissions, owners, groups, symlinks

Changed:

• Container (proprietary 7Z replaced with TAR)
• Packaging method (solid in 7Z may become streaming in XZ)
• Checksums (CRC-64 in 7Z may become CRC-32 in XZ or vice versa)

Not transferred:

• Encryption (the XZ standard does not support it)
• Solid mode in its original form (XZ works differently)
• Extended NTFS attributes (Unix specific extended attributes are different)

Comparing TXZ with Other Formats

TXZ vs TBZ2

TXZ is gradually displacing TBZ2 in modern distributions.

TXZ vs TGZ

TXZ wins in size, TGZ in speed.

TXZ vs 7Z

They use the same algorithm but different wrappers:

TXZ is chosen for Unix tasks, 7Z for Windows and maximum compression.

TXZ Compatibility and Support

Operating Systems

TXZ is the standard of modern Unix distributions:

• Linux - the tar and xz utilities are part of the standard set in any modern distribution. The command tar xJf archive.tar.xz extracts the archive in one call.
• macOS - bsdtar supports XZ since OS X 10.10 (2014). Works out of the box on modern macOS.
• FreeBSD, OpenBSD, NetBSD - tar with XZ support is built into base installations.
• Windows - the system tar command in Windows 10/11 does not support XZ directly, but 7-Zip, WinRAR, PeaZip open TXZ without issues.
• Android and iOS - third party file managers with archive support handle tar.xz.

History and Development of XZ

The XZ format has a relatively young but active history:

• 2005 - Igor Pavlov releases 7-Zip with the LZMA algorithm, demonstrating impressive compression.
• 2009 - Lasse Collin and the Tukaani Project team release XZ Utils, porting LZMA2 to the Unix toolset.
• 2013 - kernel.org switches to tar.xz as the main format for Linux kernel sources.
• 2014-2018 - major GNU projects migrate from tar.bz2 to tar.xz, RPM and DEB packages move to XZ.
• Today - XZ is the dominant compression format in Unix repositories, actively developed including with the appearance of multi threaded implementations.

Programming Languages

XZ and TAR support is built into standard libraries:

Limitations and Alternatives

When TXZ is Not Optimal

• Very frequent operations - the slow XZ compression makes it inconvenient for continuous backups with short intervals.
• Weak systems - old computers, embedded devices, and routers may not handle XZ memory requirements.
• Compatibility with old Unix - systems older than 10-15 years may not have xz in the base installation.

Alternative Scenarios

• 7Z to TAR.GZ - universal format for operational work and compatibility with old systems.
• 7Z to TAR.BZ2 - proven classic for projects of the 2000s.
• 7Z to TAR - clean container without compression for further processing.
• 7Z to ZIP - for sending to Windows users without archivers.

Conversion to TXZ is justified when a modern Unix format with maximum LZMA2 compression, native Linux tool integration, and compatibility with current repositories is needed.