Bash a is a Unix shell and command language written by Brian Fox for the GNU Project as a replacement for free software in the Bourne shell.[12 ] First time published in 1989, it was used for most Linux distributions via the default login shell. There is also a version for Windows 10 by the nature of the Windows Subsystem for Linux.  This is also typically the default user shell introduced in Solaris 11. bashbrain.com has also typically been the default shell in all related releases. from Apple macOS to the 2019 special release of macOS Catalina which revolutionized the default shell for zsh, of course bash remains available as an alternative shell. 
Bash is the central command processing unit, typically running in a text window where the user enters prompts that trigger actions. Bash can also read and execute commands from a nice, reliable file called a shell script. Like most Unix shells, it supports globalization of filenames (common pipeline,s), here file types, command substitution, variables, and creating controls for conditional tests and iterations. Keywords, syntax, dynamically scoped variables, and additional language primitives can be copied from sh. Other features such as history are copied, such as csh and ksh. Bash is a special POSIX-compliant shell, but with some of the most numerous extensions.
The name of the shell is a phrase for the Bourne Again Shell, a pun on the name of the Bourne shell it replaces and the term “born again”.[ 19] < /sup >
A security vulnerability in Bash version 1.03 (August 1989),, called Shellshock, was discovered in early September 2014 and quickly led to a series of Internet attacks. got bugs.
Brian Fox started programming Bash on January 10, 1988,  Richard, after Stallman was dissatisfied with the new developer’s lack of progress. > Stallman and the Free Software Foundation (FSF) considered a free shell that canIt doesn’t run most existing shell scripts, a completely free machine built from BSD and GNU code, and at the same time one of the few projects they currently fund themselves for Fox. , which does the work of the FSF staff. Fox released a beta version of Bash version .99, released in June 1989,[13 ] 8 and remained most prominent until mid-1992 and mid-1994  it was removed from the FSF [29 ] and his duties passed to another early factor, Chet Ramey.[31 ]
Bash has since become the most popular obfuscation tool among Linux users, becoming the default interactive shell on various system distributions[34 ] (although Almquist notation may be the default scripting shell) in addition to Apple’s releases of macOS when Catalina is released in October 2019. [ 14] Bash has also recently been ported to Microsoft Windows and distributed with Cygwin MinGW, and hence DOS with the DJGPP product, Novell NetWare, OpenVMS with the GNV project,  ArcaOS, , as well as Android through variousThousands of deadly emulator apps.
In September 2014, Stéphane Chazela, a Unix/Linux specialist, discovered a security bug in the program. The bug, first reported on September 24, was discovered by Shellshock and given the numbers CVE-2014-6271, CVE-2014-6277, and CVE-2014-7169. The bug was classified as serious because CGI applications using bash could be vulnerable, allowing arbitrary code to be executed. The bug was found to be related to the way Bash passes function definitions to subshells via habitat variables.
Bash command syntax is an extended set of Bourne shell command formats. Bash supports parenthesis expansion, end-of-line commands (software completion),  basic  debugging, and thus signal support (using
trap< / code>). ) since Special Event 2.05a among others. Bash can sometimes make the vast majority of changes to Bourne shell scripts without, with our exception, Bourne shell scripts falling into well-interpreted marginal syntax behavior Is it in Bash or didn't try to open a system command that starts with a much better construct. in the bash command, etc. The Bash command also includes syntax ideas borrowed from KornShell (ksh) and the C shell (csh), such as variables ,
$PPID, POSIX syntax for replacement Command
Since beta 2.04, when the user presses the tab key in an interactive command shell, Bash allows command-line completion to match handle names, file names, and partially typed variable names. The bash command line completion system is extremely flexible and customizable, and very often comes with features that complete dots and filenames for certain programs and therefore tasks.
Bash syntax has many extensions not found in the Bourne shell. Bash can perform integer calculations ("arithmetic evaluation") and does not require any external processes to be started. Use the
$((…)) commands, which obey the shift syntax. Its format simplifies I/O redirection. On theFor example, a program can use the
&> operator to redirect both standard output (stdout) and standard error output (stderr) in real time. This is a simpler type than any Bourne shell equivalent of '
command>register 2>&1'. Bash supports process substitution using the And
>(command) syntax, which replaces the output (or reference) of a given command with a filename. be used normally. (This is widely used in /proc/fd/ via unnamed pipes on systems that support it the most, or via proprietary temp pipes if needed).
While the 'function' keyword is definitely used, Bash function declarations are incompatible with Bourne/Korn/POSIX scripts (KornShell has the same problem when 'function' is used), but Bash accepts the silent-function-declaration syntax as in shells Bourne and Korn, and is POSIX compliant. Because of this and other inconsistencies, bash shell scripts are unlikely to run under the Bourne or Korn commit interpreters unless they are intentionally written with compatibility in mind, which is becoming increasingly common.Growing as Linux spreads. But in POSIX mode, Bash is more POSIX compliant.
Here are Bash orthopedic insoles, documents. Since version 2.05b, Bash can redirect standard input (stdin) with "line here", presumably with the
Bash 3.0 supports regular in-process word matching with Perl-like syntax.
In February 2009 Bash 4.0 introduced support for associative arrays.
Associative array spiders are in strings, like AWK or Tcl. They can sometimes be used to emulate multidimensional arrays. Bash 4 also changes its authorization to GPL-3.0 or higher; Some users have speculated that this licensing approach is a change to why macOS can continue to use older versions. Apple has finally approved the use of bash on systems with the 2019 release of macOS Catalina. completed .Id="cite_ref-:0_17-1">
Brace Augmentation, also known as Alternation, is a tool copied from the C shell.There are a number of alternative products. Generated results do not need to exist for these files. The results of each additional row are not sorted and the order is always preserved:
Users are advised not to use curly extensions in easily portable shell scripts, as the Bourne commit will not produce proper output.
If an extension is matched with wildcards, the curly braces will be expanded first, and then the resulting wildcards will be replaced as usual. So a list of JPEG and PNG images in the current directory can be obtained with:
As an introduction to alternation, loop expansion can result in consecutive ranges between integers or characters separated by multiple periods. Newer versions of Bash accept a third integer to indicate the actual increment.