Bash

Bash is a Unix shell and command language written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell. First released in 1989, it has been used as the default login shell for most Linux distributions. 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 10.15 (macOS Catalina), which changed the default shell to zsh, although Bash remains available as an alternative shell.

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.

The shell’s 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 “born again”.

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.

Python

Python is a high-level, general-purpose programming language. Its design philosophy emphasizes code readability with the use of significant indentation.

Python is dynamically typed and garbage-collected. It supports multiple programming paradigms, including structured (particularly procedural), object-oriented and functional programming. It is often described as a “batteries included” language due to its comprehensive standard library.

Guido van Rossum began working on Python in the late 1980s as a successor to the ABC programming language and first released it in 1991 as Python 0.9.0. Python 2.0 was released in 2000. Python 3.0, released in 2008, was a major revision not completely backward-compatible with earlier versions. Python 2.7.18, released in 2020, was the last release of Python 2.

Python consistently ranks as one of the most popular programming languages.

Tcl

Tcl (pronounced “tickle” or as an initialism) is a high-level, general-purpose, interpreted, dynamic programming language. It was designed with the goal of being very simple but powerful. Tcl casts everything into the mold of a command, even programming constructs like variable assignment and procedure definition. Tcl supports multiple programming paradigms, including object-oriented, imperative, functional, and procedural styles.

It is commonly used embedded into C applications, for rapid prototyping, scripted applications, GUIs, and testing. Tcl interpreters are available for many operating systems, allowing Tcl code to run on a wide variety of systems. Because Tcl is a very compact language, it is used on embedded systems platforms, both in its full form and in several other small-footprint versions.

The popular combination of Tcl with the Tk extension is referred to as Tcl/Tk (pronounced “tickle teak” or as an initialism) and enables building a graphical user interface (GUI) natively in Tcl. Tcl/Tk is included in the standard Python installation in the form of Tkinter.