Introduction<\/p>\n
\u2022 The shell lets you interact with the OS
\n\u2022 Many available shells: ksh, pdksh, bash, zsh, csh, tcsh, …
\n\u2022It is a command interpreter : each line is interpreted and executed immediately
\n\u2022A few commands are specific to the shell (cd, kill,…)
\n\u2022 Most Linux commands are programs (ls, grep, echo,…) located in \/bin or \/usr\/bin
\n\u2022Such commands are independent of the shell<\/p>\n
Bash\u00a0is a\u00a0Unix shell<\/a>\u00a0and\u00a0command language<\/a>\u00a0written by\u00a0Brian Fox<\/a>\u00a0for the\u00a0GNU Project<\/a>\u00a0as a\u00a0free software<\/a>\u00a0replacement for the\u00a0Bourne shell<\/a>. First released in 1989,\u00a0it has been used as the default\u00a0login<\/a>\u00a0shell for most\u00a0Linux<\/a>\u00a0distributions.<\/p>\n Bash was one of the first programs Linus Torvalds ported to Linux, alongside GCC. A version is also available for Windows 10 and Windows 11 via the Windows Subsystem for Linux. It is also the default user shell in Solaris 11. Bash was also the default shell in versions of Apple macOS from 10.3 (originally, the default shell was tcsh) to the 2019 release of macOS Catalina, which changed the default shell to zsh, although Bash remains available as an alternative shell.<\/p>\n Bash is a command processor that typically runs in a text window where the user types commands that cause actions. Bash can also read and execute commands from a file, called a shell script. Like most Unix shells, it supports filename globbing (wildcard matching), piping, here documents, command substitution, variables, and control structures for condition-testing and iteration. 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. Bash is a POSIX-compliant shell, but with a number of extensions.<\/p>\n The shell\u2019s name is an acronym for Bourne Again Shell, a pun on the name of the Bourne shell that it replaces and the notion of being \u201cborn again\u201d.<\/p>\n A security hole in Bash dating from version 1.03 (August 1989), dubbed Shellshock, was discovered in early September 2014 and quickly led to a range of attacks across the Internet. Patches to fix the bugs were made available soon after the bugs were identified.<\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":"