81-623: The Linux Kernel Developers Summit (also known as the Linux Kernel Maintainer Summit ) is an annual gathering of the top Linux kernel developers. Attendance at the summit is by invitation only, and the conference was first held in San Jose in March, 2001. It was organized by Theodore Ts'o to provide a face to face venue for kernel developers to discuss current and future issues surrounding Linux kernel development, and
162-528: A task switcher in Intel 80386 assembly language and a terminal driver . On 25 August 1991, Torvalds posted the following to comp.os.minix , a newsgroup on Usenet : I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones. This has been brewing since April, and is starting to get ready. I'd like any feedback on things people like/dislike in minix, as my OS resembles it somewhat (same physical layout of
243-455: A version control system thus far, in 2002, Linux developers adopted BitKeeper , which was made freely available to them even though it was not free software . In 2005, because of efforts to reverse-engineer it, the company which owned the software revoked its support of the Linux community. In response, Torvalds and others wrote Git . The new system was written within weeks, and in two months
324-599: A "...person who has made a renewed or confirmed commitment .... " Whatever the original touchstone may have been, in the end the program received the name, "the Bourne Again SHell ." The acronym of that name then is "bash," a word meaning "to strike violently. " In the context of computer programming, to "violently hit something," such as a computer keyboard, could be considered a hyperbolic image of some frustration . Such imagery of negative emotionality could be seen as standing in direct juxtaposition to
405-581: A Linux Kernel Code of Conflict was introduced on 8 March 2015. It was replaced on 16 September 2018 by a new Code of Conduct based on the Contributor Covenant . This coincided with a public apology by Torvalds and a brief break from kernel development. On 30 November 2018, complying with the Code of Conduct , Jarkko Sakkinen of Intel sent out patches replacing instances of "fuck" appearing in source code comments with suitable versions focused on
486-441: A bit in that more features were made available throughout the series, including support for Bluetooth , Logical Volume Manager (LVM) version 1, RAID support, InterMezzo and ext3 file systems. Version 2.6.0 was released on 17 December 2003. The development for 2.6. x changed further towards including new features throughout the series. Among the changes that have been made in the 2.6 series are: integration of μClinux into
567-482: A concurrent execution of command1 and command2, they must be executed in the Bash shell in the following way: In this case command1 is executed in the background & symbol, returning immediately control to the shell that executes command2 in the foreground. A process can be stopped and control returned to bash by typing Ctrl + z while the process is running in the foreground. A list of all processes, both in
648-399: A different order than the documented Bash startup sequence. The default content of the root user's files may also have issues, as well as the skeleton files the system provides to new user accounts upon setup. The startup scripts that launch the X window system may also do surprising things with the user's Bash startup scripts in an attempt to set up user-environment variables before launching
729-413: A listing of JPEG and PNG images in the current directory could be obtained using: In addition to alternation, brace expansion can be used for sequential ranges between two integers or characters separated by double dots. Newer versions of Bash allow a third integer to specify the increment. When brace expansion is combined with variable expansion (A.K.A. parameter expansion and parameter substitution )
810-415: A manner similar to AWK or Tcl . They can be used to emulate multidimensional arrays. Bash 4 also switches its license to GPL-3.0-or-later ; some users suspect this licensing change is why macOS continues to use older versions. Zsh became the default shell in macOS with the release of macOS Catalina in 2019. Brace expansion, also called alternation, is a feature copied from the C shell . It generates
891-468: A percent sign: Bash supplies "conditional execution" command separators that make execution of a command contingent on the exit code set by a precedent command. For example: Where ./do_something is only executed if the cd (change directory) command was "successful" (returned an exit status of zero) and the echo command would only be executed if either the cd or the ./do_something command return an "error" (non-zero exit status). For all commands
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#1732779543524972-408: A process to the foreground, while bg sets a stopped process running in the background. bg and fg can take a job id as their first argument, to specify the process to act on. Without one, they use the default process, identified by a plus sign in the output of jobs . The kill command can be used to end a process prematurely, by sending it a signal . The job id must be specified after
1053-586: A rich set of features, including: Bash also offers... The keywords , syntax , dynamically scoped variables and other basic features of the language are all copied from sh . Other features, e.g., history , are copied from csh and ksh . The Bash command syntax is a superset of the Bourne shell command syntax. Bash supports brace expansion , command line completion (Programmable Completion), basic debugging and signal handling (using trap ) since bash 2.05a among other features. Bash can execute
1134-483: A roadmap, there are technical guidelines. Instead of a central resource allocation, there are persons and companies who all have a stake in the further development of the Linux kernel, quite independently from one another: People like Linus Torvalds and I don’t plan the kernel evolution. We don’t sit there and think up the roadmap for the next two years, then assign resources to the various new features. That's because we don’t have any resources. The resources are all owned by
1215-494: A set of alternative combinations. Generated results need not exist as files. The results of each expanded string are not sorted and left to right order is preserved: Users should not use brace expansions in portable shell scripts, because the Bourne shell does not produce the same output. When brace expansion is combined with wildcards, the braces are expanded first, and then the resulting wildcards are substituted normally. Hence,
1296-514: A study issued by the Linux Foundation, covering the commits for the releases 4.8 to 4.13, about 1500 developers were contributing from about 200–250 companies on average. The top 30 developers contributed a little more than 16% of the code. For companies, the top contributors are Intel (13.1%) and Red Hat (7.2%), Linaro (5.6%), IBM (4.1%), the second and fifth places are held by the 'none' (8.2%) and 'unknown' (4.1%) categories. Instead of
1377-446: A versatile tool in various computing environments. As a command processor , Bash operates within a text window where users input commands to execute various tasks. It also supports the execution of commands from files, known as shell scripts , facilitating automation . In keeping with Unix shell conventions, Bash incorporates a rich set of features. The keywords , syntax , dynamically scoped variables and other basic features of
1458-561: Is monolithic in an architectural sense since the entire OS runs in kernel space . Linux is provided under the GNU General Public License version 2 , although it contains files under other compatible licenses . In April 1991, Linus Torvalds, a 21-year-old computer science student at the University of Helsinki started working on an operating system, inspired by UNIX, for a personal computer. He started with
1539-495: Is a monolithic kernel rather than a microkernel was the topic of a debate between Andrew S. Tanenbaum , the creator of MINIX, and Torvalds. The Tanenbaum–Torvalds debate started in 1992 on the Usenet group comp.os.minix as a general discussion about kernel architectures. Version 0.95 was the first capable of running the X Window System . In March 1994, Linux 1.0.0 was released with 176,250 lines of code. As indicated by
1620-515: Is a play on words, referencing both its predecessor, the Bourne shell, and the concept of rebirth . Since its inception, Bash has gained widespread adoption and is commonly used as the default login shell for numerous Linux distributions. It holds historical significance as one of the earliest programs ported to Linux by Linus Torvalds , alongside the GNU Compiler ( GCC ). It is available on nearly all modern operating systems, making it
1701-541: Is becoming less common as Linux becomes more widespread. But in POSIX mode, Bash conforms with POSIX more closely. Bash supports here documents . Since version 2.05b Bash can redirect standard input (stdin) from a "here string" using the <<< operator. Bash 3.0 supports in-process regular expression matching using a syntax reminiscent of Perl . In February 2009, Bash 4.0 introduced support for associative arrays . Associative array indices are strings, in
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#17327795435241782-516: Is compatible with the Bourne shell and gives semantics similar to csh for the ~/.bashrc and ~/.bash_login . The [ -r filename ] && cmd is a short-circuit evaluation that tests if filename exists and is readable, skipping the part after the && if it is not. Some versions of Unix and Linux contain Bash system startup scripts, generally under the /etc directory. Bash executes these files as part of its standard initialization, but other startup files can read them in
1863-551: Is mailed to the Bash maintainers (or optionally to other email addresses). Bash supports programmable completion via built-in complete , compopt , and compgen commands. The feature has been available since the beta version of 2.04 released in 2000. These commands enable complex and intelligent completion specification for commands (i.e. installed programs), functions, variables, and filenames. The complete and compopt two commands specify how arguments of some available commands or options are going to be listed in
1944-486: Is often packaged with functions that complete arguments and filenames for specific programs and tasks. Bash's syntax has many extensions lacking in the Bourne shell. Bash can perform integer calculations ("arithmetic evaluation") without spawning external processes. It uses the ((...)) command and the $ ((...)) variable syntax for this purpose. Its syntax simplifies I/O redirection . For example, it can redirect standard output (stdout) and standard error (stderr) at
2025-552: Is significantly responsible for rising use of Linux overall. The cost to redevelop version 2.6.0 of the Linux kernel in a traditional proprietary development setting has been estimated to be US$ 612 million (€467M, £394M) in 2004 prices using the COCOMO person-month estimation model. In 2006, a study funded by the European Union put the redevelopment cost of kernel version 2.6.8 higher, at €882M ($ 1.14bn, £744M). This topic
2106-451: Is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the kernel for the GNU operating system (OS) which was created to be a free replacement for Unix . Since the late 1990s, it has been included in many operating system distributions , many of which are called Linux . One such Linux kernel operating system is Android which
2187-444: Is used in many mobile and embedded devices. Most of the kernel code is written in C as supported by the GNU compiler collection (GCC) which has extensions beyond standard C. The code also contains assembly code for architecture-specific logic such as optimizing memory use and task execution. The kernel has a modular design such that modules can be integrated as software components – including dynamically loaded. The kernel
2268-525: The DJGPP project, to Novell NetWare , to OpenVMS by the GNU project, to ArcaOS , and to Android via various terminal emulation applications. In September 2014, Stéphane Chazelas, a Unix/Linux specialist, discovered a security bug in the program. The bug, first disclosed on September 24, was named Shellshock and assigned the numbers CVE - 2014-6271 , CVE- 2014-6277 and CVE- 2014-7169 . The bug
2349-605: The Native POSIX Thread Library (NPTL), User-mode Linux integration into the mainline kernel sources, SELinux integration into the mainline kernel sources, InfiniBand support, and considerably more. Starting with 2.6.x releases, the kernel supported a large number of file systems; some designed for Linux, like ext3 , ext4 , FUSE , Btrfs , and others native to other operating systems like JFS , XFS , Minix, Xenix , Irix , Solaris , System V , Windows and MS-DOS . Though development had not used
2430-1066: The atomic CMPXCHG instruction introduced with the i486 to allow reliable mutexes —making the 3.7 kernel series the last one still supporting the original processor. The same series unified support for the ARM processor. The numbering change from 2.6.39 to 3.0, and from 3.19 to 4.0, involved no meaningful technical differentiation; the major version number was increased simply to avoid large minor numbers. Stable 3.x.y kernels were released until 3.19 in February 2015. Version 3.11, released on 2 September 2013, added many new features such as new O_TMPFILE flag for open(2) to reduce temporary file vulnerabilities, experimental AMD Radeon dynamic power management, low-latency network polling, and zswap (compressed swap cache). In April 2015, Torvalds released kernel version 4.0. By February 2015, Linux had received contributions from nearly 12,000 programmers from more than 1,200 companies, including some of
2511-543: The dash shell), while a script intending to support pre-POSIX Bourne shells, like autoconf 's configure , are even more limited in the features they can use. Bash uses GNU Readline to provide keyboard shortcuts for command line editing using the default ( Emacs ) key bindings. Vi-bindings can be enabled by running set -o vi . The Bash shell has two modes of execution for commands: batch (asynchronous), and concurrent (synchronous). To execute commands in batch mode (i.e., in sequence) they must be separated by
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2592-654: The image of childbirth. With that pun, it would seem, is added an allusion : possibly to the Hindu or Buddhist idea of reincarnation ; possibly to the Christian idiom known as "being born again ;" or quite possibly just to the more abstract idea of renewal . While numerous English translations of the Christian New Testament , Book of John , chapter 3 do contain the words "born again," Merriam-Webster 's dictionary has "born-again" defined as
2673-534: The language are all copied from the Bourne shell , sh . Other features, e.g., history , are copied from the C shell , csh , and the Korn Shell , ksh . Bash is a POSIX -compliant shell with a number of extensions. While Bash was developed for UNIX and UNIX-like operating systems such as GNU/Linux, it is also available on Windows, BeOS, and Haiku. Brian Fox began coding Bash on January 10, 1988, after Richard Stallman became dissatisfied with
2754-449: The readline input. As of version 5.1 completion of the command or the option is usually activated by the Tab ↹ keystroke after typing its name. The program's name is a figure of speech or witticism which begins with an homage to Stephen Bourne , the creator of one of the shell programs which have sometimes been considered superseded by the bash shell. His name is used as a pun on
2835-558: The window manager . These issues can often be addressed using a ~/.xsession or ~/.xprofile file to read the ~/.profile — which provides the environment variables that Bash shell windows spawned from the window manager need, such as xterm or Gnome Terminal . Invoking Bash with the --posix option or stating set -o posix in a script causes Bash to conform very closely to the POSIX 1003.2 standard . Bash shell scripts intended for portability should take into account at least
2916-515: The "core," including architecture-specific code, kernel code, and mm code, while 60% is drivers. Contributions are submitted as patches, in the form of text messages on the Linux kernel mailing list (LKML) (and often also on other mailing lists dedicated to particular subsystems). The patches must conform to a set of rules and to a formal language that, among other things, describes which lines of code are to be deleted and what others are to be added to
2997-576: The "ftp.funet.fi" – FTP server of the Finnish University and Research Network ( FUNET ). It was not even executable since its code still needed Minix to compile and test it. On 5 October 1991, Torvalds announced the first "official" version of Linux, version 0.02. [As] I mentioned a month ago, I'm working on a free version of a Minix-lookalike for AT-386 computers. It has finally reached the stage where it's even usable (though may not be depending on what you want), and I am willing to put out
3078-517: The 'function' keyword, Bash function declarations are not compatible with Bourne/Korn/POSIX scripts (the KornShell has the same problem when using 'function'), but Bash accepts the same function declaration syntax as the Bourne and Korn shells, and is POSIX-conformant. Because of these and other differences, Bash shell scripts are rarely runnable under the Bourne or Korn shell interpreters unless deliberately written with that compatibility in mind, which
3159-762: The AMD Radeon FreeSync and NVIDIA Xavier display, fixes for F2FS , EXT4 and XFS , restored support for swap files on the Btrfs file system and continued work on the Intel Icelake Gen11 graphics and on the NXP i.MX8 SoCs. This release was noticeably larger than the rest, Torvalds mentioning that "The overall changes for all of the 5.0 release are much bigger." A total of 1,991 developers, of whom 334 were first-time collaborators, added more than 553,000 lines of code to version 5.8, breaking
3240-420: The European Union. As of 7 March 2011 , using then-current LOC (lines of code) of a 2.6.x Linux kernel and wage numbers with David A. Wheeler's calculations it would cost approximately $ 3bn (about €2.2bn) to redevelop the Linux kernel as it keeps getting bigger. An updated calculation as of 26 September 2018 , using then-current 20,088,609 LOC (lines of code) for the 4.14.14 Linux kernel and
3321-549: The Linux 2.2.13 code for the support of the S/390 architecture. Version 2.4.0, released on 4 January 2001, contained support for ISA Plug and Play , USB , and PC Cards . Linux 2.4 added support for the Pentium 4 and Itanium (the latter introduced the ia64 ISA that was jointly developed by Intel and Hewlett-Packard to supersede the older PA-RISC ), and for the newer 64-bit MIPS processor. Development for 2.4. x changed
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3402-673: The Linux kernel for its OS. Torvalds labeled the kernel with major version 0 to indicate that it was not yet intended for general use. Version 0.11, released in December 1991, was the first version to be self-hosted ; compiled on a computer running the Linux kernel. When Torvalds released version 0.12 in February 1992, he adopted the GNU General Public License version 2 (GPLv2) over his previous self-drafted license, which had not permitted commercial redistribution. In contrast to Unix , all source files of Linux are freely available, including device drivers . The initial success of Linux
3483-424: The POSIX shell standard. Some bash features not found in POSIX are: If a piece of code uses such a feature, it is called a "bashism" – a problem for portable use. Debian's checkbashisms and Vidar Holen's shellcheck can be used to make sure that a script does not contain these parts. The list varies depending on the actual target shell: Debian's policy allows some extensions in their scripts (as they are in
3564-403: The background and stopped, can be achieved by running jobs : In the output, the number in brackets refers to the job id. The plus sign signifies the default process for bg and fg . The text "Running" and "Stopped" refer to the process state . The last string is the command that started the process. The state of a process can be changed using various commands. The fg command brings
3645-459: The change will either be submitted as a single patch or in multiple patches of source code . In case of a single subsystem that is maintained by a single maintainer, these patches are sent as e-mails to the maintainer of the subsystem with the appropriate mailing list in Cc. The maintainer and the readers of the mailing list will review the patches and provide feedback. Once the review process has finished
3726-421: The character ";", or on separate lines: In this example, when command1 is finished, command2 is executed, and when command2 has completed, command3 will execute. A background execution of command1 can occur using (symbol &) at the end of an execution command, and process will be executed in background while immediately returning control to the shell and allowing continued execution of commands. Or to have
3807-413: The current US national average programmer salary of $ 75,506 show that it would cost approximately $ 14,725,449,000 (£11,191,341,000) to rewrite the existing code. Most who use Linux do so via a Linux distribution . Some distributions ship the vanilla or stable kernel. However, several vendors (such as Red Hat and Debian ) maintain a customized source tree. These are usually updated at a slower pace than
3888-409: The directory stack, the $ RANDOM and $ PPID variables, and POSIX command substitution syntax $ (...) . When a user presses the tab key within an interactive command-shell, Bash automatically uses command line completion , since beta version 2.04, to match partly typed program names, filenames and variable names. The Bash command-line completion system is very flexible and customizable, and
3969-408: The exit status is stored in the special variable $ ? . Bash also supports if ... ; then ... ; else ... ; fi and case $ VARIABLE in $ pattern ) ... ;; $ other_pattern ) ... ;; esac forms of conditional command evaluation. An external command called bashbug reports Bash shell bugs. When the command is invoked, it brings up the user's default editor with a form to fill in. The form
4050-530: The file-system (due to practical reasons) among other things). I've currently ported bash (1.08) and gcc (1.40), and things seem to work. This implies that I'll get something practical within a few months [...] Yes - it's free of any minix code, and it has a multi-threaded fs. It is NOT protable [ sic ] (uses 386 task switching etc), and it probably never will support anything other than AT-harddisks, as that's all I have :-(. On 17 September 1991, Torvalds prepared version 0.01 of Linux and put on
4131-416: The first official kernel made using it was released. In 2005 the stable team was formed as a response to the lack of a kernel tree where people could work on bug fixes , and it would keep updating stable versions. In February 2008 the linux-next tree was created to serve as a place where patches aimed to be merged during the next development cycle gathered. Several subsystem maintainers also adopted
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#17327795435244212-454: The idea of becoming "born again." The naming could be considered an instance of verbal irony or accidental innuendo . Bash grammar was initially based on the grammars of the most popular Unix shell programs then currently in use, some of which were considered particularly difficult to use or frustrating at that time. As the years progressed, bash development has made its grammar more user-friendly, so much so that it seems likely that
4293-589: The kernel community at the 2017 Embedded Linux Conference Europe. The issues brought up were discussed a few days later at the Maintainers Summit. Concerns over the lack of consistency in how maintainers responded to patches submitted by developers were echoed by Shuah Khan , the maintainer of the kernel self-test framework. Torvalds contended that there would never be consistency in the handling of patches because different kernel subsystems have, over time, adopted different development processes. Therefore, it
4374-570: The kernel so that old programs would work. Version 3.0 was released on 22 July 2011. On 30 May 2011, Torvalds announced that the big change was "NOTHING. Absolutely nothing." and asked, "...let's make sure we really make the next release not just an all new shiny number, but a good kernel too." After the expected 6–7 weeks of the development process, it would be released near the 20th anniversary of Linux. On 11 December 2012, Torvalds decided to reduce kernel complexity by removing support for i386 processors—specifically by not having to emulate
4455-492: The kernel summit was the decision to move to a rolling stable 2.6 kernel every few months, instead of the formerly used model utilizing a 1–2-year development cycle. The Linux Technical Advisory Board is elected at a bird-of-a-feather session at the Linux Kernel Summit. The summit usually hosts around 80 attendees. Linux kernel The Linux kernel is a free and open source , UNIX-like kernel that
4536-406: The kernel with system software (e.g., the GNU C Library , systemd , and other Unix utilities and daemons ) and a wide selection of application software , but their usage share in desktops is low in comparison to other operating systems. Since Android , which is Linux, accounts for the majority of mobile device operating systems, and due to its rising use in embedded devices , Android
4617-525: The lack of progress being made by a prior developer. Stallman and the FSF considered a free shell that could run existing shell scripts so strategic to a completely free system built from BSD and GNU code that this was one of the few projects they funded themselves, with Fox undertaking the work as an employee of FSF. Fox released Bash as a beta, version .99, on June 8, 1989, and remained the primary maintainer until sometime between mid-1992 and mid-1994, when he
4698-471: The linux.conf.au (LCA) conference in 2018, developers expressed the view that the culture of the community has gotten much better in the past few years. Daniel Vetter, the maintainer of the Intel drm/i915 graphics kernel driver, commented that the "rather violent language and discussion" in the kernel community has decreased or disappeared. Laurent Pinchart asked developers for feedback on their experiences with
4779-537: The mainline kernel sources, PAE support, support for several new lines of CPUs , integration of Advanced Linux Sound Architecture (ALSA) into the mainline kernel sources, support for up to 2 users (up from 2 ), support for up to 2 process IDs (64-bit only, 32-bit architectures still limited to 2 ), substantially increased the number of device types and the number of devices of each type, improved 64-bit support, support for file systems which support file sizes of up to 16 terabytes , in-kernel preemption , support for
4860-547: The previous kernel version. The Git kernel source tree names all developers who have contributed to the Linux kernel in the Credits directory and all subsystem maintainers are listed in Maintainers . As with many large open-source software projects, developers are required to adhere to the Contributor Covenant , a code of conduct intended to address harassment of minority contributors. Additionally, to prevent offense
4941-532: The record previously held by version 4.9. According to the Stack Overflow's annual Developer Survey of 2019, more than the 53% of all respondents have developed software for Linux and about 27% for Android , although only about 25% develop with Linux-based operating systems. Most websites run on Linux-based operating systems , and all of the world's 500 most powerful supercomputers use some form of OS based on Linux. Linux distributions bundle
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#17327795435245022-473: The same time using the &> operator. This is simpler to type than the Bourne shell equivalent ' command > file 2>&1 '. Bash supports process substitution using the <(command) and >(command) syntax, which substitutes the output of (or input to) a command where a filename is normally used. (This is implemented through /proc/fd/ unnamed pipes on systems that support that, or via temporary named pipes where necessary). When using
5103-576: The sources for wider distribution. It is just version 0.02...but I've successfully run bash, gcc, gnu-make, gnu-sed, compress, etc. under it. Linux grew rapidly as many developers, including the MINIX community, contributed to the project. At the time, the GNU Project had completed many components for its free UNIX replacement, the GNU OS , but its kernel, GNU Hurd , was incomplete. The project adopted
5184-437: The specified files. These patches can be automatically processed so that system administrators can apply them in order to make just some changes to the code or to incrementally upgrade to the next version. Linux is distributed also in GNU zip (gzip) and bzip2 formats. A developer who wants to change the Linux kernel writes and tests a code change. Depending on how significant the change is and how many subsystems it modifies,
5265-407: The subsystem maintainer accepts the patches in the relevant Git kernel tree. If the changes to the Linux kernel are bug fixes that are considered important enough, a pull request for the patches will be sent to Torvalds within a few days. Otherwise, a pull request will be sent to Torvalds during the next merge window. The merge window usually lasts two weeks and starts immediately after the release of
5346-507: The suffix -next for trees containing code which they mean to submit for inclusion in the next release cycle. As of January 2014 , the in-development version of Linux is held in an unstable branch named linux-next . The 20th anniversary of Linux was celebrated by Torvalds in July 2011 with the release of version 3.0.0. As 2.6 had been the version number for 8 years, a new uname26 personality that reports 3.x as 2.6.40+x had to be added to
5427-543: The use of inclusive terminology within the source code is mandated. Bash (Unix shell) Bash , short for Bourne-Again SHell , is a shell program and command language supported by the Free Software Foundation and first developed for the GNU Project by Brian Fox . Designed as a 100% free software alternative for the Bourne shell , it was initially released in 1989. Its moniker
5508-407: The vanilla branch, and they usually include all fixes from the relevant stable branch, but at the same time they can also add support for drivers or features which had not been released in the vanilla version the distribution vendor started basing its branch from. The community of Linux kernel developers comprises about 5000–6000 members. According to the "2017 State of Linux Kernel Development",
5589-474: The variable expansion is performed after the brace expansion, which in some cases may necessitate the use of the eval built-in, thus: ‹The template How-to is being considered for merging .› When Bash starts, it executes the commands in a variety of dot files . Unlike Bash shell scripts, dot files do typically have neither the execute permission enabled nor an interpreter directive like #!/bin/bash . The example ~/.bash_profile below
5670-444: The various corporations who use and contribute to Linux, as well as by the various independent contributors out there. It's those people who own the resources who decide... Notable conflicts among Linux kernel developers: Prominent Linux kernel developers have been aware of the importance of avoiding conflicts between developers. For a long time there was no code of conduct for kernel developers due to opposition by Torvalds. However,
5751-414: The vast majority of Bourne shell scripts without modification, with the exception of Bourne shell scripts stumbling into fringe syntax behavior interpreted differently in Bash or attempting to run a system command matching a newer Bash builtin, etc. Bash command syntax includes ideas drawn from the Korn Shell (ksh) and the C shell (csh) such as command line editing, command history ( history command),
5832-949: The version number, it was the first version considered suitable for a production environment . In June 1996, after release 1.3, Torvalds decided that Linux had evolved enough to warrant a new major number, and so labeled the next release as version 2.0.0. Significant features of 2.0 included symmetric multiprocessing (SMP), support for more processors types and support for selecting specific hardware targets and for enabling architecture-specific features and optimizations. The make *config family of commands of kbuild enable and configure options for building ad hoc kernel executables ( vmlinux ) and loadable modules. Version 2.2, released on 20 January 1999, improved locking granularity and SMP management, added m68k , PowerPC , Sparc64 , Alpha , and other 64-bit platforms support. Furthermore, it added new file systems including Microsoft 's NTFS read-only capability. In 1999, IBM published its patches to
5913-719: The word 'hug'. Developers who feel treated unfairly can report this to the Linux Foundation Technical Advisory Board. In July 2013, the maintainer of the USB 3.0 driver Sage Sharp asked Torvalds to address the abusive commentary in the kernel development community. In 2014, Sharp backed out of Linux kernel development, saying that "The focus on technical excellence, in combination with overloaded maintainers, and people with different cultural and social norms, means that Linux kernel maintainers are often blunt, rude, or brutal to get their job done". At
5994-519: The world's largest software and hardware vendors. Version 4.1 of Linux, released in June 2015, contains over 19.5 million lines of code contributed by almost 14,000 programmers. Linus Torvalds announced that kernel version 4.22 would instead be numbered 5.0 in March 2019, stating that "'5.0' doesn't mean anything more than that the 4.x numbers started getting big enough that I ran out of fingers and toes." It featured many major additions such as support for
6075-448: Was agreed upon that each kernel subsystem maintainer would document the rules for patch acceptance. Linux is evolution, not intelligent design ! The kernel source code, a.k.a. source tree, is managed in the Git version control system – also created by Torvalds. As of 2021 , the 5.11 release of the Linux kernel had around 30.34 million lines of code. Roughly 14% of the code is part of
6156-493: Was driven by programmers and testers across the world. With the support of the POSIX APIs, through the libC that, whether needed, acts as an entry point to the kernel address space, Linux could run software and applications that had been developed for Unix. On 19 January 1992, the first post to the new newsgroup alt.os.linux was submitted. On 31 March 1992, the newsgroup was renamed comp.os.linux . The fact that Linux
6237-683: Was initially run by Usenix and then VA Linux's Open Source Developer's Network . Subsequent summits from 2002 to 2006 were held the two days prior to the Ottawa Linux Symposium in Ottawa, Ontario, Canada at the same conference center with Usenix providing all of the logistical support. The 2007 Kernel Summit was held on 4–6 September 2007 at the DeVere University Arms Hotel in Cambridge , England , and
6318-510: Was laid off from FSF and his responsibility was transitioned to another early contributor, Chet Ramey. Since then, Bash has become by far the most popular shell among users of Linux, becoming the default interactive shell on that operating system's various distributions and on Apple's macOS releases before Catalina in October 2019. Bash has also been ported to Microsoft Windows and distributed with Cygwin and MinGW , to DOS by
6399-505: Was regarded as severe, since CGI scripts using Bash could be vulnerable, enabling arbitrary code execution . The bug was related to how Bash passes function definitions to subshells through environment variables . As a command processor , Bash operates within a text window where users input commands to execute various tasks. It also supports the execution of commands from files, known as shell scripts , facilitating automation . In keeping with Unix shell conventions, Bash incorporates
6480-509: Was revisited in October 2008 by Amanda McPherson, Brian Proffitt, and Ron Hale-Evans. Using David A. Wheeler's methodology, they estimated redevelopment of the 2.6.25 kernel now costs $ 1.3bn (part of a total $ 10.8bn to redevelop Fedora 9). Again, Garcia-Garcia and Alonso de Magdaleno from University of Oviedo (Spain) estimate that the value annually added to kernel was about €100M between 2005 and 2007 and €225M in 2008, it would cost also more than €1bn (about $ 1.4bn as of February 2010) to develop in
6561-404: Was the first time the summit was moved outside of North America. The discussions at the kernel summit have traditionally been highly technical, with a focus on issues that were not getting resolution via electronic mail. In recent years, however, the summit has been gradually focusing more on higher level development process issues. An example of an important development process decision made at
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