Red Hat Enterprise Linux Explained

Red Hat Enterprise Linux
Developer:Red Hat, Inc.
Family:Linux (Unix-like)
Released:[1]
Source Model:Open source
Latest Preview Version:9 Beta
Latest Preview Date:[2]
Marketing Target:Commercial market (servers, mainframes, supercomputers, workstations)
Kernel Type:Monolithic (Linux)
Working State:Current
Supported Platforms:x86-64
ARM64; IBM Z; IBM Power Systems[3]
Updatemodel:Software Updater
Language:Multilingual
Userland:GNU
Ui:GNOME Shell, Bash
License:Various free software licenses, plus proprietary binary blobs[4]
Preceded By:Red Hat Linux

Red Hat Enterprise Linux (RHEL) is a commercial open-source[5] [6] [7] Linux distribution[8] developed by Red Hat for the commercial market. Red Hat Enterprise Linux is released in server versions for x86-64, Power ISA, ARM64, and IBM Z and a desktop version for x86-64. Fedora Linux and CentOS Stream serve as its upstream sources. All of Red Hat's official support and training, together with the Red Hat Certification Program, focuses on the Red Hat Enterprise Linux platform.

The first version of Red Hat Enterprise Linux to bear the name originally came onto the market as "Red Hat Linux Advanced Server". In 2003, Red Hat rebranded Red Hat Linux Advanced Server to "Red Hat Enterprise Linux AS"[9] and added two more variants, Red Hat Enterprise Linux ES and Red Hat Enterprise Linux WS.[10]

Red Hat previously used strict trademark rules to restrict free re-distribution of their officially supported versions of Red Hat Enterprise Linux[11] but still freely provided its source code. Third-party derivatives were able to be built and redistributed by stripping away non-free components like Red Hat's trademarks. Examples include community-supported distributions like Rocky Linux and AlmaLinux, and commercial ones like Oracle Linux. In 2023, Red Hat decided to stop making the source code of Red Hat Enterprise Linux available to the public. The code is still available to Red Hat customers, as well as developers using free accounts, though under conditions that forbid redistribution of the source code.

Variants

Red Hat Enterprise Linux Server subscription is available at no cost for development purposes.[12] Developers need to register for the Red Hat Developer Program and agree to license terms forbidding production use and redistribution of the source code.[13] This free developer subscription was announced on March 31, 2016.

There are also "Academic" editions of the Desktop and Server variants.[14] They are offered to schools and students, are less expensive, and are provided with Red Hat technical support as an optional extra. Web support based on the number of customer contacts can be purchased separately.

It is often assumed the branding ES, AS, and WS stand for "Entry-level Server",[15] [16] "Advanced Server" and "Work Station", respectively. The reason for this is that the ES product is indeed the company's base enterprise server product, while AS is the more advanced product. However, nowhere on its site or in its literature does Red Hat say what AS, ES, and WS stand for.

In Red Hat Enterprise Linux 5 there are new editions that substitute former Red Hat Enterprise Linux AS/ES/WS/Desktop:[17] [18]

Red Hat had also announced its Red Hat Global Desktop Linux edition "for emerging markets".[19]

RHEL 4, 3, and prior releases had four variants:

Relationship with Fedora Linux

The Fedora Project provides the following explanation:[20]

Fedora is a free distribution and community project and upstream for Red Hat Enterprise Linux. Fedora is a general purpose system that gives Red Hat and the rest of its contributor community the chance to innovate rapidly with new technologies. Red Hat Enterprise Linux is a commercial enterprise operating system and has its own set of test phases including alpha and beta releases which are separate and distinct from Fedora development.
Originally, Red Hat sold boxed versions of Red Hat Linux directly to consumers and business through phone support. The Fedora Project began in 2002 as a set of community supported packages for Red Hat Linux. However, the six month release cycle of Red Hat Linux was too disruptive for business users and Red Hat wanted a more reliable revenue stream. In 2002 Red Hat began releasing Red Hat Enterprise Linux based on Red Hat Linux, but with a much more conservative release cycle and a subscription based support program. A year later, Red Hat discontinued the Red Hat Linux product line, merging it with the Fedora community packages and releasing the resulting Fedora distribution for free.[21]

RHEL source code is also not freely available, as those that obtain it are forbidden from redistribution.[13] For example, RHEL 5 was forked from Fedora at the end of 2006 (approximately at the time of the Fedora Core 6 release) and released more or less together with Fedora 14. By the time RHEL 6 was released, many features from Fedora 13 and 14 had already been backported into it. The Fedora Project lists the following lineages for older Red Hat Enterprise releases:

In addition, the Fedora project publishes a set of packages for RHEL called the Extra Packages for Enterprise Linux (EPEL). EPEL packages can be expected to work in RHEL, but it is up to willing community members to maintain the packages and back port any upstream changes. As such, packages "may come and go" during the ten-year lifespan of the RHEL release and Red Hat support plans do not include resolving issues caused by EPEL packages.[24]

Derivatives

See main article: article and Red Hat Enterprise Linux derivatives.

Originally, Red Hat's enterprise product, then known as Red Hat Linux, was made freely available to anybody who wished to download it, while Red Hat made money from support. Red Hat then moved towards splitting its product line into Red Hat Enterprise Linux which was designed to be stable and with long-term support for enterprise users and Fedora as the community distribution and project sponsored by Red Hat. The use of trademarks prevents verbatim copying of Red Hat Enterprise Linux.

Red Hat Enterprise Linux is derived completely from free and open source software. Until 2023, Red Hat made the source code to its enterprise distribution publicly available through its FTP website. Accordingly, several groups used the source code to compile their own derivatives, typically with changes including the removal of any references to Red Hat's trademarks and pointing the update systems to non-Red Hat servers. Groups which have undertaken this include AlmaLinux, CentOS, MIRACLE LINUX, Oracle Linux, CloudLinux OS, Rocky Linux, Scientific Linux, StartCom Enterprise Linux, Pie Box Enterprise Linux, X/OS, Lineox, and Bull's XBAS for high-performance computing.[25] However, as of June 2023, Red Hat no longer makes the source code freely available; while they still provide the source code to customers and developers.[13] The GNU GPL forbids terms and conditions that prevent users from redistributing the source code of GPL-licensed software, including but not limited to the GNU core utilities (such as cat, ls, and rm), which is licensed under the GNU GPLv3 or later as of version 6.10, and the Linux kernel itself (licensed under the GPLv2 only).[26] [27] [28] This led to AlmaLinux, one of the RHEL derivative Linux distributions, moving away from "1:1 bug for bug" compatibility to "application binary interface (ABI) compatible", while Oracle, SUSE, and CIQ (the company behind Rocky Linux) collaborated to form the Open Enterprise Linux Association (OpenELA) in order to provide "open and free Enterprise Linux (EL) source code".[29] [30]

Derivatives of Red Hat Enterprise Linux are free but do not get any commercial support or consulting services from Red Hat and lack software, hardware or security certifications from Red Hat. They also do not get access to Red Hat services like Red Hat Network.

Unusually, Red Hat took steps to obfuscate their changes to the Linux kernel for RHEL 6.0 by not publicly providing the patch files for their changes in the source tarball, and only releasing the finished product in source form. Speculation suggested that the move was made to affect Oracle's competing rebuild and support services, which further modifies the distribution. This practice however, still complies with the GNU GPL since source code is defined as "[the] preferred form of the work for making modifications to it", and the distribution still complies with this definition.[31] Red Hat's CTO Brian Stevens later confirmed the change, stating that certain information (such as patch information) would now only be provided to paying customers to make the Red Hat product more competitive against the growing number of companies offering support for products based on RHEL. CentOS developers had no objections to the change since they do not make any changes to the kernel beyond what is provided by Red Hat.[32] Their competitor Oracle announced in November 2012 that they were releasing a RedPatch service, which allows public view of the RHEL kernel changes, broken down by patch.[33] [34]

Related products and add-ons

See also: Commercial products based on Red Hat Enterprise Linux.

A number of commercial vendors use Red Hat Enterprise Linux as a base for the operating system in their products. Two of the best known are the Console Operating System in VMware ESX Server and Oracle Linux.

Version history and timeline

Naming convention

Each release is given a codename which is selected by a vote of the developers. The codenames don't have a specific pattern (unlike Ubuntu or Debian).

RHEL 9

Red Hat Enterprise Linux 9 was announced at Red Hat Summit on May 10, 2022, and was officially released on .[35] In this version of the system introduced a Linux Kernel 5.14.0 and Gnome 40.

RHEL 9 was the first to be based on CentOS Stream, itself based on Fedora Linux, while historically RHEL was based directly on Fedora Linux.[36]

The first beta for Red Hat Enterprise Linux 9 (Plow), based on Fedora Linux 34, was released on November 3, 2021.

Red Hat Enterprise Linux 9 (Plow) was released on May 18, 2022.[37] The name Plow was the Appalachian Trail nickname for Tim Burke, one of the founders of RHEL and retired leader of RHEL engineering.[38]

RHEL 8

Red Hat Enterprise Linux 8 (Ootpa) is based on Fedora 28, upstream Linux kernel 4.18, GCC 8.2, glibc 2.28, systemd 239, GNOME 3.28, and the switch to Wayland. The first beta was announced on November 14, 2018.[39] Red Hat Enterprise Linux 8 was officially released on .[40]

With Release 8 of Red Hat Enterprise Linux, IBM has completed transition of POWER8 and POWER9 servers tolittle-endian mode.[41] [42] [43]

The name Ootpa was a tribute to Larry Troan. His son, Eric Troan was Red Hat's first head engineer and his username was ewt, so his father was given the name ewt's pa, pronounced Ootpa.[38]

RHEL 7

Red Hat Enterprise Linux 7 (Maipo) is based on Fedora 18 and Fedora 19, upstream Linux kernel 3.10, systemd 208 (updated to 219 in RHEL 7.2), and GNOME 3.8 (rebased to GNOME 3.28 in RHEL 7.6) The first beta was announced on 11 December 2013,[46] [47] and a release candidate was made available on 15 April 2014.[48] On Red Hat Enterprise Linux 7 was officially released.[49]

RHEL 6

Red Hat Enterprise Linux 6 was forked from Fedora 10 and contains many backported features from Fedora 11 and Fedora 12.

RHEL 5

Red Hat Enterprise Linux 5 has forked with Fedora Core 6.

RHEL 4

RHEL 4 introduced Linux kernel 2.6 versions and extended attributes on ext2 and ext3 file systems.[62]

RHEL 3

RHEL 2.1

Product life cycle

The life cycle of Red Hat Enterprise Linux is at least seven years for versions 3 and 4, and spans at least 10 years for versions 5, 6, 7, 8 and 9. The life cycle comprises several phases of varying length with different degrees of support. During the first phase ("Production 1"), Red Hat provides full support and updates software and hardware drivers. In later phases ("Production 2" and "Production 3"), only security and other important fixes are provided and support for new hardware is gradually reduced.[65]

In the last years of the support lifecycle (after seven years for version 4 and earlier, and after 10 years for version 5 and later), critical and security-related fixes are only provided to customers who pay an additional subscription ("Extended Lifecycle Support Add-On") that is available for versions 3, 4, 5 and 6. This covers a limited number of packages.[66] Red Hat only supports major version upgrades from version 6 to version 7 and from version 7 to version 8.[67]

RHEL
version 		Last minor
release 		Release date End of Full Support End of Maintenance
Support 1 (RHEL 5, 6, 7) 		End of
Maintenance Support (RHEL 8, 9),
Maintenance Support 2 (RHEL 5, 6, 7)
(product retirement) 		End of Extended
Lifecycle Support
U-726 March 2002 (AS)
1 May 2003 (ES)		30 November 200431 May 200531 May 2009[68]
U-923 October 200320 July 200630 June 200731 October 2010[69] 30 January 2014
U-914 February 200531 March 200916 February 201129 February 201231 March 2017
5.1115 March 20078 January 201331 January 201431 March 201730 November 2020
6.1010 November 201010 May 201610 May 201730 November 202030 June 2024
7.910 June 2014[70] 6 August 20196 August 202030 June 202430 June 2028[71]
8.107 May 2019May 2024May 202931 May 2031[72]
9.408 Nov 2022May 2027May 203231 May 2034

Kernel backporting

To maintain a stable application binary interface (ABI), Red Hat does not update the kernel version, but instead backports new features to the same kernel version with which a particular version of RHEL has been released. New features are backported throughout the Production 1 phase of the RHEL lifecycle.[73] Consequently, RHEL may use a Linux kernel with a dated version number, yet the kernel is up-to-date regarding not only security fixes, but also certain features.[74] One specific example is the socket option which was added to Linux kernel 3.9, and was subsequently backported and became available since RHEL 6.5, which uses version 2.6.32 of the Linux kernel.[75] [76] [77]

Extended Update Support (EUS) / Z Tree

The Extended Update Support (EUS) allows an organization / company to choose when they change to a new minor version. For the first 6 months of the EUS channel / yum repo, features may be added, but then the channel is locked down so that only bug and security fixes are patched. The organization / company then has 24 months to move to a new EUS branch. EUS allows the organization / company to stay on a minor version if required by a third-party application which is only tested with a particular minor version of RHEL, such as Oracle Database, IBM Db2, IBM Cloud Orchestrator, Hortonworks. There may also be extra costs associated with using the EUS repos/channels depending on the agreement the organization / company has with Red Hat.[78] For more information on what is Included/Excluded from the EUS see.[78]

Note

Updates

In general one can move from z streams to the next version of the z stream.

Any 7.y.z EUS channel where y is greater than 1.The standard base channel for Red Hat Enterprise Linux 7, which is the most recent minor release aka rhel 7Y where y is the latest greatest.

One can not go back in time, aka 7.5.z to 7.4.z and will NOT be supported.[78]

RHEL 6

Red Hat Enterprise Linux 6 was forked from Fedora 12 and contains many backported features from Fedora 13 and 14.

RHEL 7

Red Hat Enterprise Linux 7 (Maipo) is based on Fedora 19, upstream Linux kernel 3.10, 10 June 2014, uses Linux kernel 3.10.0-123[63]

RHEL 8

Red Hat Enterprise Linux 8 (Ootpa) is based on Fedora 28, upstream Linux kernel 4.18, systemd 239, and GNOME 3.28. The first beta was announced on 14 November 2018.[39] Red Hat Enterprise Linux 8 was officially released on .[40]

For RHEL 8, the update schedule is approximately:[84]

RHEL 8 application streams

In addition to normal OS updates, RHEL 8 also maintains application streams to allow for certain applications to be supported and updated independent of the base OS and to match the maintenance stream of the application vendor.[86] Each application stream will be supported from two to five years with new versions only available during the Red Hat Enterprise Linux Full Support Phase.[87] These apps should be expected to be updated frequently with shorter lifecycles than the base OS packages.

Packages currently offered as streams[87]

RHEL 9

See also

Further reading

External links

Notes and References

  1. Red Hat Enterprise Edition Product Line Optimizes Solutions for Top e-Business Applications . . February 22, 2000 . February 20, 2020.
  2. Web site: What's new in Red Hat Enterprise Linux 9 Beta. Gil. Cattelain. Joe. Brockmeier. 2021-11-03. 2021-11-03. Red Hat.
  3. Web site: 9.0 Release Notes - Chapter 2. Architectures . Red Hat Customer Portal . . 2022-12-26.
  4. Web site: Explaining Why We Don't Endorse Other Systems . . March 13, 2011.
  5. Web site: Why choose Red Hat for Linux? . 2024-01-01 . www.redhat.com . https://web.archive.org/web/20231231083827/https://www.redhat.com/en/topics/linux/why-choose-red-hat-enterprise-linux . 2023-12-31 . en.
  6. News: Lardinois . Frederic . 2023-07-11 . Why SUSE is forking Red Hat Enterprise Linux . 2024-01-01 . . https://archive.today/20240101230458/https://techcrunch.com/2023/07/11/why-suse-is-forking-red-hat-enterprise-linux/ . 2024-01-01. en-US.
  7. News: Dickens . Steven . The Future Of Open-Source Enterprise Linux And Community Collaboration . 2023-08-16 . 2024-01-01 . . https://web.archive.org/web/20240101230934/https://www.forbes.com/sites/stevendickens/2023/08/16/the-future-of-open-source-enterprise-linux-and-community-collaboration/ . 2024-01-01 . en.
  8. Web site: Bradley M. . Kuhn . A Comprehensive Analysis of the GPL Issues With the Red Hat Enterprise Linux (RHEL) Business Model . Software Freedom Conservancy . 25 June 2023.
  9. Web site: 2003-04-07 . redhat.com Red Hat Enterprise Linux . https://web.archive.org/web/20030407171319/http://redhat.com/software/rhel/ . dead . 2003-04-07 . 2024-06-05 .
  10. Azhar . Arslan . Red Hat Enterprise Linux .
  11. Web site: ESR: "We Don't Need the GPL Anymore". onlamp.com. 2008-03-04. 2018-04-17. https://web.archive.org/web/20180417163519/http://www.onlamp.com/pub/a/onlamp/2005/06/30/esr_interview.html. dead.
  12. Web site: Downloads: Red Hat Developers. 9 April 2018. Red Hat.
  13. News: Proven . Liam . Red Hat strikes a crushing blow against RHEL downstreams . 24 June 2023 . The Register . 23 June 2023 . en.
  14. Web site: Enterprise Linux Academic Subscriptions . Red Hat.
  15. Web site: 2003-04-16 . redhat.com ES . https://web.archive.org/web/20030416204939/http://www.redhat.com/software/rhel/es/ . dead . 2003-04-16 . 2024-06-05 .
  16. Web site: 2006-03-15 . redhat.com Enterprise Linux . https://web.archive.org/web/20060315035550/https://www.redhat.com/rhel/ . dead . 2006-03-15 . 2024-06-05 .
  17. Web site: Moving to Red Hat Enterprise Linux 5 . Red Hat . 2009-12-02 . dead . https://web.archive.org/web/20091008223755/http://www.redhat.com/rhel/moving/ . October 8, 2009 .
  18. Web site: Red Hat Enterprise Linux Server Version Comparison Chart. Red Hat. https://web.archive.org/web/20100105045954/http://www.redhat.com/rhel/compare/. 2010-01-05.
  19. Web site: Red Hat Global Desktop Linux: The Best Kept Secret? . linuxtoday.com . 2007-08-05 . 2007-10-14 . https://web.archive.org/web/20071014043444/http://www.linuxtoday.com/news_story.php3?ltsn=2007-08-03-031-26-OP-RH-SW . dead .
  20. Web site: Fedora project wiki, the difference between Fedora Linux and RHEL. fedoraproject.org. 2010-05-23.
  21. Web site: Fedora project wiki, History of Red Hat Linux. fedoraproject.org. 2010-05-23.
  22. Web site: Red Hat Enterprise Linux Release Dates. Red Hat Customer Portal. en. 2019-06-17.
  23. Web site: Red Hat Enterprise Linux 9 is now available . Red Hat Customer Portal. 25 October 2021 . en. 2022-04-04.
  24. Web site: What's EPEL, and how do I use it?. November 21, 2019. Red Hat Blog.
  25. Web site: SLURM at CEA. 2011-03-21. 2013-05-24. https://web.archive.org/web/20130524225601/https://computing.llnl.gov/linux/slurm/slurm_ug_2010/01-mh-cea.pdf. dead.
  26. Web site: June 29, 2007 . GNU General Public License v3.0 . August 31, 2023 . . "You may make, run and propagate covered works that you do not convey, without conditions so long as your license otherwise remains in force.".
  27. Web site: June 29, 2007 . GNU General Public License v3.0 . August 31, 2023 . . "You may convey verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice; keep intact all notices stating that this License and any non-permissive terms added in accord with section 7 apply to the code; keep intact all notices of the absence of any warranty; and give all recipients a copy of this License along with the Program.".
  28. Web site: June 29, 2007 . GNU General Public License v3.0 . August 31, 2023 . . "You may not impose any further restrictions on the exercise of the rights granted or affirmed under this License. For example, you may not impose a license fee, royalty, or other charge for exercise of rights granted under this License...".
  29. Web site: CIQ, Oracle and SUSE Create Open Enterprise Linux... . 2023-08-31 . www.suse.com . . en.
  30. Web site: August 10, 2023 . CIQ, Oracle and SUSE Create Open Enterprise Linux Association for a Collaborative and Open Future . Oracle.
  31. Web site: Controversy surrounds Red Hat's "obfuscated" source code release. The H. 12 March 2011.
  32. Web site: Red Hat defends changes to kernel source distribution. The H. 12 March 2011.
  33. Web site: Oracle: Get your Red Hat Linux patches from us, it's easier. New service lets public browse kernel fixes. The Register. 1 August 2014. Neil. McAllister. 12 Nov 2012.
  34. Web site: Project: RedPatch . oss.oracle.com . 2014-08-04.
  35. Web site: Red Hat Defines a New Epicenter for Innovation with Red Hat Enterprise Linux 9 . Red Hat, Inc. . 2022-05-11 . 2022-05-10.
  36. Hot Off the Presses: Red Hat Enterprise Linux 9 . Cattelain, Gil . May 18, 2022 . May 19, 2022.
  37. Web site: Hot Off the Presses: Red Hat Enterprise Linux 9 . 25 May 2022.
  38. Web site: RHEL Codename Conventions . Red Hat Learning Community . 23 May 2022 . 31 May 2022 . English.
  39. Web site: Powering IT's future while preserving the present: Introducing Red Hat Enterprise Linux 8 Beta. 2018-11-14.
  40. Web site: Red Hat Open the Linux Experience to Every Enterprise, Every Cloud, and Every Workload with Red Hat Enterprise Linux 8. 7 May 2019 . 2019-05-07.
  41. Web site: IBM . IBM United States Software Announcement 219-234 . IBM . 28 May 2019 . International Business Machines Corporation . 26 March 2022.
  42. Web site: IBM . IBM United States Software Announcement 219-234 . IBM . International Business Machines Corporation . 26 March 2022.
  43. Web site: Timothy Prickett Morgan . The Transition To RHEL 8 Begins On Power Systems . ITJungle . 10 June 2019 . 26 March 2022.
  44. Web site: Red Hat Enterprise Linux 8.1 adds live Linux kernel patching. Steven J.. Vaughan-Nichols. November 5, 2019. ZDNet. 2019-11-06.
  45. Web site: RHEL 8.4 - Final Release. Red Hat Customer Portal. 17 September 2021 .
  46. Web site: Red Hat Announces Availability of Red Hat Enterprise Linux 7 Beta. 2013-12-11. 2013-12-11. Red Hat.
  47. Web site: 2013 Red Hat Summit. See for example this presentation
  48. Web site: Red Hat Enterprise Linux 7 Release Candidate Now Available. 2014-04-15. redhat.com. https://web.archive.org/web/20140427065858/http://www.redhat.com/about/news/archive/2014/4/red-hat-enterprise-linux-7rc-available. 2014-04-27. dead. 2014-04-27.
  49. Web site: Red Hat Unveils Red Hat Enterprise Linux 7. 2014-06-10. redhat.com. 2014-06-10.
  50. Web site: Red Hat Continues Platform Innovation with the General Availability of the First Minor Release of Red Hat Enterprise Linux 7. www.redhat.com. 5 March 2015 .
  51. Web site: Red Hat Enterprise Linux 7.2 now available. 2015-11-19. Red Hat, Inc.. 2015-11-19.
  52. Web site: Red Hat Enterprise Linux 7.3 now available - Red Hat Customer Portal. access.redhat.com. 3 November 2016 . 2016-11-03.
  53. Web site: Red Hat Enterprise Linux 7.4 now available. access.redhat.com. August 2017 . 2017-08-01.
  54. Web site: Red Hat Enterprise Linux 7.5 Released. access.redhat.com. 10 April 2018 . 2018-04-10.
  55. Web site: Chapter 8. Desktop Red Hat Enterprise Linux 7. Red Hat Customer Portal.
  56. Web site: Red Hat Refines Hybrid Cloud Innovation with Latest Version of the World's Leading Enterprise Linux Platform, Red Hat Enterprise Linux 7.6. access.redhat.com. 30 October 2018 . 2018-10-30.
  57. Web site: Red Hat Drives Cloud-Native Flexibility, Enhances Operational Security with Latest Version of Red Hat Enterprise Linux 7. access.redhat.com. 6 August 2019 . 2019-08-06.
  58. Web site: Red Hat Enterprise Linux 7.8 Now Generally Available. access.redhat.com. 31 March 2020 . 2020-03-31.
  59. Web site: Announcing Red Hat Enterprise Linux 7.9. access.redhat.com. 30 September 2020 . 2020-10-13.
  60. https://access.redhat.com/support/policy/updates/errata Red Hat Enterprise Linux Life Cycle
  61. Web site: 6.0 Release Notes — Red Hat Enterprise Linux 6. Red Hat Customer Portal.
  62. Web site: Red Hat Enterprise Linux AS 4 Release Notes . 2019-04-24 . 2019-04-24 . https://web.archive.org/web/20190424090732/https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/4/html/Release_Notes/as-x86/index.html . dead .
  63. Web site: Red Hat Enterprise Linux Updates and Related Kernel Versions. Red Hat . 2012-05-16.
  64. Web site: New redhat-release package for Red Hat Enterprise Linux 2.1 Update 7. Red Hat Customer Portal. 2012-05-16. dead. https://web.archive.org/web/20120311123129/https://rhn.redhat.com/errata/RHBA-2005-362.html. 2012-03-11.
  65. Web site: Red Hat Enterprise Linux Life Cycle . Access.redhat.com . 2015-01-20.
  66. Web site: What is the Red Hat Enterprise Linux Extended Life Cycle Support Add-On (ELS), and what is its support life cycle? . Red Hat . 2017-01-12 .
  67. Web site: Does Red Hat support upgrades between major versions of Red Hat Enterprise Linux?. 10 February 2023 .
  68. Web site: Red Hat Enterprise Linux Errata Support Policy . https://web.archive.org/web/20100405103331/https://www.redhat.com/security/updates/errata/ . 2010-04-05 . Red Hat . 2012-08-11.
  69. Web site: Red Hat Enterprise Linux 3 - End Of Life . Red Hat . 2010-01-12.
  70. Web site: Red Hat Enterprise Linux Release Dates. Red Hat . 2015-09-30.
  71. Web site: Announcing up to 4 years of Extended Life Cycle Support (ELS) for Red Hat Enterprise Linux 7 . 2024-05-17 . www.redhat.com . en.
  72. Web site: Red Hat Enterprise Linux Life Cycle. Red Hat . 2022-10-14.
  73. Web site: What is backporting and how does it affect Red Hat Enterprise Linux (RHEL)? . 12 May 2016. subscription.
  74. Web site: Why does Red Hat Linux use such an old kernel?. stackexchange.com.
  75. Web site: SO_REUSEPORT on linux. StackOverflow.com. 12 May 2016.
  76. Web site: Backport SO_REUSEPORT patch from kernel 3.9+ to help support haproxy graceful restart. 12 May 2016. subscription.
  77. Web site: Which RHEL version supports the SO_REUSEPORT socket option?. 15 October 2014 . Red Hat. subscription.
  78. Web site: Red Hat Enterprise Linux (RHEL) Extended Update Support (EUS) Overview. Red Hat Customer Portal. 18 November 2022 .
  79. Web site: [CentOS] Z-Stream? ]. Johnny . Hughes . 20 May 2012.
  80. Web site: Red Hat Enterprise Linux Life Cycle. Red Hat Customer Portal.
  81. Web site: Red Hat Enterprise Linux Life Cycle. 2020-11-21. Red Hat Customer Portal. en.
  82. Web site: Red Hat Enterprise Linux 7.8 Now Generally Available. 2020-11-21. Red Hat Customer Portal. 31 March 2020 . en.
  83. Web site: Announcing Red Hat Enterprise Linux 7.9. 2020-11-21. Red Hat Customer Portal. 30 September 2020 . en.
  84. Web site: Red Hat Enterprise Linux Life Cycle. 2019-08-06.
  85. Web site: Red Hat Enterprise Linux Release Dates. Red Hat Customer Portal. 17 May 2023 .
  86. Web site: Red Hat Enterprise Linux Life Cycle. 2019-08-06. sec. "Red Hat Enterprise Linux 8 Application Streams Life Cycle". Red Hat Customer Portal.
  87. Web site: Red Hat Enterprise Linux 8 Application Streams Life Cycle. 2019-08-06.

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