TheLinux Standard Base (LSB) was a joint project by severalLinux distributions^[which?] under the organizational structure of theLinux Foundation to standardize the software system structure, including theFilesystem Hierarchy Standard. LSB was based on thePOSIX specification, theSingle UNIX Specification (SUS), and several other open standards, but extended them in certain areas.

Linux Standard Base

The LSB logo
Abbreviation	LSB
Status	Published
First published	June 29, 2001 (2001-06-29)
Latest version	5.0 June 2, 2015
Committee	ISO/IEC JTC 1/SC 22
Series	ISO/IEC 23360
Base standards	POSIX,SUS
Domain	Software compatibility

According to LSB:

The goal of the LSB is to develop and promote a set of open standards that will increase compatibility among Linux distributions and enable software applications to run on any compliant systemeven in binary form. In addition, the LSB will help coordinate efforts to recruit software vendors to port and write products for Linux Operating Systems.

LSB compliance might be certified for a product by a certification procedure.^[1]

LSB specified standardlibraries (centered around theld-lsb.so), a number of commands and utilities that extend thePOSIX standard, the layout of thefile system hierarchy,run levels, the printing system, includingspoolers such asCUPS and tools likeFoomatic, and several extensions to theX Window System. It also specified boot facilities, such as$local_fs,$network, which were used to indicate service dependencies inSystem V-style initialization scripts.^[2] A machine readable comment block at the top of a script provided the information necessary to determine at which point of the initialization process the script should be invoked; it was called the LSB header.^[3]

The commandlsb_release -a was available in many systems to get the LSB version details, or could be made available by installing an appropriate package, for example theredhat-lsb package inRed-Hat-flavored distributions such asFedora,^[4] or thelsb-release package in Debian-based distributions.

The standard stopped being updated in 2015 and current Linux distributions do not adhere to or offer it; however, thelsb_release command is sometimes still available.^{[citation needed]} On February 7, 2023, a former maintainer of the LSB wrote, "The LSB project is essentially abandoned."^[5]

LSB was designed to be binary-compatible and produced a stableapplication binary interface (ABI) forindependent software vendors.

To provide backward compatibility, the LSB adopted an interface deprecation policy to give application developers enough time to adapt in case an interface was removed from LSB. An interface that is to be removed would first be marked as deprecated in an LSB release; that interface would still be supported in that release and at least two subsequent LSB releases. This allowed the developer to rely on every interface in LSB for a known time and also to plan for changes.^[6]

LSB 5.0 was the first major release that brokebackward compatibility with earlier versions, as it removedQt 3; applications dynamically linked with Qt 3 libraries were not guaranteed to run on all LSB 5.0-compliant distributions.^[7]

• 1.0: Initial release June 29, 2001.
• 1.1: Released January 22, 2002. Added hardware-specific specifications (IA-32).
• 1.2: Released June 28, 2002. Added hardware-specific specifications (PowerPC32-bit). Certification began July 2002.
• 1.2.1: Released October 2002. AddedItanium.
• 1.3: Released December 17, 2002. Added hardware-specific specifications (Itanium, Enterprise System Architecture/390, z/Architecture).
• 2.0: Released August 31, 2004
  • LSB is modularized to LSB-Core, LSB-CXX, LSB-Graphics, and LSB-I18n (not released)
  • New hardware-specific specifications (PowerPC64-bit,AMD64)
  • Synchronized toSingle UNIX Specification (SUS) version 3
• 2.0.1: Released October 21, 2004,ISO version of LSB 2.0, which included specification for all hardware architectures (except LSB-Graphics, of which only a generic version is available).
• 2.1: Released March 11, 2005.
• 3.0: Released July 1, 2005. Among other library changes:
  • GNU C Library version 2.3.4
  • C++ ABI is changed to the one used bygcc 3.4
  • The core specification is updated to ISOPOSIX (2003)
  • Technical Corrigenda 1: 2005
• 3.1: Released October 31, 2005. This version has been submitted as ISO/IEC 23360:2006.
• 3.2: Released January 28, 2008. This version has been submitted as ISO/IEC 23360:2006.
• 4.0: Released November 11, 2008. This version contains the following features:
  • GNU C Library version 2.4
  • Binary compatibility with LSB 3.x
  • Easier to useSDK
  • Support for newer versions ofGTK andCairo graphical libraries
  • Java (optional module)
  • Simpler ways of creating LSB-compliant RPM packages
  • Crypto API (via theNetwork Security Services library) (optional module)
• 4.1: Released February 16, 2011:^[8]
  • Java removed^[9]
  • "Trial Use" modules from LSB 4.0, covering multimedia (ALSA), security (NSS) and desktop miscellaneous (xdg-utils) have been promoted as required submodules
  • UpdatedGTK+, Cairo andCUPS libraries
  • Three new test suites added
• 5.0: Released June 2, 2015, This version has been submitted as ISO/IEC 23360:2021
  • GNU C Library version 2.10 (for psiginfo)
  • First major release that breaks backward compatibility with earlier versions (compatible with LSB 3.0, and mostly compatible with LSB 3.1 and later, with some exceptions^[10])
  • Incorporates the changes made inFHS 3.0
  • Qt 3 library has been removed
  • Evolved module strategy; LSB is modularized to LSB Core, LSB Desktop, LSB Languages, LSB Imaging, and LSB Trial Use

The LSB, version 3.1, is registered as an officialISO/IEC international standard. The main parts of it are:

• ISO/IEC 23360-1:2006 Linux Standard Base (LSB) core specification 3.1 — Part 1: Generic specification^[11]
• ISO/IEC 23360-2:2006 Linux Standard Base (LSB) core specification 3.1 — Part 2: Specification for IA-32 architecture
• ISO/IEC 23360-3:2006 Linux Standard Base (LSB) core specification 3.1 — Part 3: Specification for IA-64 architecture
• ISO/IEC 23360-4:2006 Linux Standard Base (LSB) core specification 3.1 — Part 4: Specification for AMD64 architecture
• ISO/IEC 23360-5:2006 Linux Standard Base (LSB) core specification 3.1 — Part 5: Specification forPPC32 architecture
• ISO/IEC 23360-6:2006 Linux Standard Base (LSB) core specification 3.1 — Part 6: Specification forPPC64 architecture
• ISO/IEC 23360-7:2006 Linux Standard Base (LSB) core specification 3.1 — Part 7: Specification forS390 architecture
• ISO/IEC 23360-8:2006 Linux Standard Base (LSB) core specification 3.1 — Part 8: Specification forS390X architecture

There is also ISO/IEC TR 24715:2006 which identifies areas of conflict between ISO/IEC 23360 (the Linux Standard Base 3.1 specification) and the ISO/IEC 9945:2003 (POSIX) International Standard.^[12]

The LSB, version 5.0, is also registered as an officialISO/IEC international standard.

• ISO/IEC 23360-1-1:2021 Linux Standard Base (LSB) — Part 1-1: Common definitions
• ISO/IEC 23360-1-2:2021 Linux Standard Base (LSB) — Part 1-2: Core specification generic part
• ISO/IEC 23360-1-3:2021 Linux Standard Base (LSB) — Part 1-3: Desktop specification generic part
• ISO/IEC 23360-1-4:2021 Linux Standard Base (LSB) — Part 1-4: Languages specification
• ISO/IEC 23360-1-5:2021 Linux Standard Base (LSB) — Part 1-5: Imaging specification
• ISO/IEC TS 23360-1-6:2021 Linux Standard Base (LSB) — Part 1-6: Graphics and Gtk3 specification
• ISO/IEC 23360-2-2:2021 Linux Standard Base (LSB) — Part 2-2: Core specification for X86-32 architecture
• ISO/IEC 23360-2-3:2021 Linux Standard Base (LSB) — Part 2-3: Desktop specification for X86-32 architecture
• ISO/IEC 23360-3-2:2021 Linux Standard Base (LSB) — Part 3-2: Core specification for IA64 (Itanium™) architecture
• ISO/IEC 23360-3-3:2021 Linux Standard Base (LSB) — Part 3-3: Desktop specification for IA64 (Itanium TM) architecture
• ISO/IEC 23360-4-2:2021 Linux Standard Base (LSB) — Part 4-2: Core specification for AMD64 (X86-64) architecture
• ISO/IEC 23360-4-3:2021 Linux Standard Base (LSB) — Part 4-3: Desktop specification for AMD64 (X86-64) architecture
• ISO/IEC 23360-5-2:2021 Linux Standard Base (LSB) — Part 5-2: Core specification for PowerPC 32 architecture
• ISO/IEC 23360-5-3:2021 Linux Standard Base (LSB) — Part 5-3: Desktop specification for PowerPC 32 architecture
• ISO/IEC 23360-6-2:2021 Linux Standard Base (LSB) — Part 6-2: Core specification for PowerPC 64 architecture
• ISO/IEC 23360-6-3:2021 Linux Standard Base (LSB) — Part 6-3: Desktop specification for PowerPC 64 architecture
• ISO/IEC 23360-7-2:2021 Linux Standard Base (LSB) — Part 7-2: Core specification for S390 architecture
• ISO/IEC 23360-7-3:2021 Linux Standard Base (LSB) — Part 7-3: Desktop specification for S390 architecture
• ISO/IEC 23360-8-2:2021 Linux Standard Base (LSB) — Part 8-2: Core specification for S390X architecture
• ISO/IEC 23360-8-3:2021 Linux Standard Base (LSB) — Part 8-3: Desktop specification for S390X architecture

ISO/IEC 23360 and ISO/IEC TR 24715 can be freely downloaded from ISO website.^[13]

While LSB was a standard and without a competitor, it was followed only by fewLinux distributions. For instance, only 21 distribution releases (versions) were certified for LSB version 4.0, notablyRed Flag Linux Desktop 6.0,Red Hat Enterprise Linux 6.0,SUSE Linux Enterprise 11, andUbuntu 9.04 (Jaunty Jackalope);^[14] even fewer were certified for version 4.1.

The LSB was criticized^{[15][16][17][18]} for not taking input from projects, most notably theDebian project, outside the sphere of its member companies.

LSB specified that software packages should either be delivered as an LSB-compliant installer,^[19] or (preferably) be delivered in a restricted form of theRPM Package Manager format.^[20]

This choice of package format precluded the use of other existing package formats not compatible with RPM. To address this, the standard did not dictate which package format the system must use for its own packages, merely that RPM must be supported to allow packages from third-party distributors to be installed on a conforming system.

Debian included optional support for LSB early on, at version 1.1 in "woody" (3.0; July 19, 2002), 2.0 in "sarge" (3.1; June 6, 2005), 3.1 in "etch" (4.0; April 8, 2007), 3.2 in "lenny" (5.0; February 14, 2009) and 4.1 in "wheezy" (7; May 4, 2013). To use foreign LSB-compliant RPM packages, theend-user needs to use Debian'sAlien program to transform them into the native package format and then install them.

The LSB-specified RPM format had a restricted subset of RPM features—to block usage of RPM features that would be untranslatable to .deb with Alien or other package conversion programs, and vice versa, as each format has capabilities the other lacks. In practice, not all Linux binary packages were necessarily LSB-compliant, so while most could be converted between .rpm and .deb, this operation was restricted to a subset of packages.

By using Alien, Debian was LSB-compatible for all intents and purposes, but according to the description of theirlsb package,^[21] the presence of the package "does not imply that we believe that Debian fully complies with the Linux Standard Base, and should not be construed as a statement that Debian is LSB-compliant."^[21]

Debian strived to comply with the LSB, but with many limitations.^[22] However, this effort ceased around July 2015 due to lack of interest and workforce inside the project.^[23] In September 2015, the Debian project confirmed that while support forFilesystem Hierarchy Standard (FHS) would continue, support for LSB had been dropped.^[24] Ubuntu followed Debian in November 2015.^[25]

Additionally, the compliance test suites were criticized for being buggy and incomplete—most notably, in 2005Ulrich Drepper criticized the LSB for poorly written tests which can cause incompatibility between LSB-certified distributions when some implement incorrect behavior to make buggy tests work, while others apply for and receive waivers from complying with the tests.^[26] He also denounced a lack of application testing, pointing out that testing only distributions can never solve the problem of applications relying on implementation-defined behavior.^[26]

For the vendors considering LSB certifications in their portability efforts, theLinux Foundation sponsored a tool that analyzed and provided guidance on symbols and libraries that go beyond the LSB.^[27]

• Intel Binary Compatibility Standard (iBCS)
• POSIX (Portable Operating System Interface)

• Linux Standard Base Specifications Archive, linuxfoundation.org
• Linux Standard Base (LSB), wiki.linuxfoundation.org
• Open Linux VERification (OLVER) Project, linuxtesting.org
• search for lsb packages, pkgs.org
• lsb, pkgs.org
• lsb in Launchpad, launchpad.net - bug reports

Media:

• Additional Vendors Participate in Growing LSB Effort, 1998, debian.org - describes the breakdown of teams (at the time) and who was involved, of historical interest
• Four Linux Vendors Agree On An LSB Implementation, 2004, slashdot.org
• Yes, the LSB Has Value, 2005, licquia.org – response to Drepper by Jeff Licquia