mscompress

mscompress [options] [infile [outfile]]

• infile: The path to the LZX-compressed file to be decompressed. If omitted, mscompress reads from standard input.
• outfile: The path where the decompressed data should be written. If omitted, mscompress writes to standard output.

-V
    Displays the version information for mscompress and exits.

-c
    Forces output to standard output (stdout), even if an output file could be inferred. This is often the default behavior if no output file is specified.

-f
    Forces overwriting of existing output files without prompting.

-o OUTFILE
    Specifies the path to the output file where the decompressed data will be written.

mscompress is a specialized Linux command-line utility designed to decompress files that have been compressed using Microsoft's LZX algorithm. This compression method is predominantly found within Microsoft Cabinet (.cab) files, which were historically used for software distribution, driver packages, and system files in Windows operating systems.

Unlike general-purpose compression tools like gzip or bzip2, mscompress is not intended for standard Unix file compression. Its specific role is to enable Linux users to extract content from LZX-compressed streams embedded within these proprietary Microsoft archives. It typically reads the LZX-compressed data from an input file (or standard input) and writes the decompressed raw data to standard output or a specified output file. It is often used as a backend component by tools like cabextract, which parse the .cab file structure and then call mscompress to handle the LZX-compressed components.

mscompress is a highly specialized tool exclusively designed for the Microsoft LZX compression algorithm. It cannot decompress files compressed with other algorithms (e.g., MSZIP, ZIP, Deflate, BZIP2, LZMA). Its functionality is often integrated into broader tools like cabextract, which handle the overall structure of Microsoft Cabinet files. Users seeking general-purpose compression/decompression should look to standard Unix utilities. It may not be actively maintained as a standalone utility, and its direct usage is less common now compared to using higher-level archive tools.

mscompress is not a general-purpose compression or decompression tool. It is singularly focused on the LZX compression algorithm, a proprietary method developed by Microsoft. This distinguishes it significantly from standard Unix compression tools like gzip or bzip2, which use different algorithms (DEFLATE and BZIP2, respectively). Users should understand this specificity; attempting to decompress files compressed with other methods using mscompress will result in errors.

While mscompress can be run directly, its most common and practical application is as an underlying component for more comprehensive archive extraction utilities, particularly cabextract. cabextract handles the parsing of the .cab file format's structure, extracts individual components, and then often calls mscompress (or similar internal routines) to decompress any streams that were specifically compressed with LZX. This makes mscompress an important, albeit often invisible, part of the .cab file extraction ecosystem on Linux.

mscompress emerged as a crucial utility for Linux users needing to interact with Microsoft's proprietary LZX-compressed data streams. Its development was driven by the prevalence of Microsoft Cabinet (.cab) files in the late 1990s and early 2000s, used extensively for distributing Windows system updates, drivers, and application installers. As a standalone tool, or more commonly as a component of projects like cabextract, it allowed non-Windows operating systems to extract and utilize content from these archives. Its primary role was to bridge the gap between Unix-like environments and the specific compression technology employed by Microsoft, enabling interoperability without requiring a Windows environment for decompression. While direct use is less common today, its functionality remains relevant for legacy .cab file handling.

cabextract(1), gzip(1), bzip2(1), xz(1), unzip(1)