Command line interpreter

A command line interpreter is a computer program which reads lines of text that the user types and interprets them in the context of a given operating system or programming language.

Examples of command line interpreters:

the various Unix shell programs such as Bash
command.com (DOS, Windows)
cmd.exe (OS/2, Windows NT)
Windows PowerShell (Windows)
4DOS (DOS, Windows)
4NT (Windows NT)
TSO under MVS
CMS under VM/CMS
CL for OS/400
clig for tcl/c command line interpreter generation
DOSBox (various operating systems and platforms)
Basic-Plus under RSTS/E

Command interpreters as user interfaces

Command line interpreters allow users to issue various commands in a very efficient (and often terse) way. This requires the user to know the names of the commands and their parameters, and the syntax of the language that is interpreted. From the 1960s onwards, user interaction with computers was primarily by means of command line interfaces.

In the 1970s, researchers began to develop graphical user interfaces (GUIs) to provide an alternative user interface for computers, whereby commands were represented by pictorial operations, rather than as textual descriptions. Since they are easier to learn than command line interfaces, they have become the most common way of interacting with a computer. However, command line interpreters remain widely used in conjunction with GUIs. For some complex tasks, the latter are less effective because of the large number of menus and dialog boxes presented and because of the innate difficulty of representing the underlying task graphically.

Scripting

Most command line interpreters support scripting, to various extents. (They are, after all, interpreters of an interpreted programming language, albeit that in many cases the language is unique to the particular command line interpreter.) They will interpret scripts (variously termed shell scripts or batch files) written in the language that they interpret. Some command line interpreters also incorporate the interpreter engines of other languages, such as REXX, in addition to their own, allowing the executing of scripts, in those languages, directly within the command line interpreter itself.

Conversely, scripting programming languages, in particular those with an eval function (such as REXX, Perl, Python, or Jython), can be used to implement command line interpreters. For a few operating systems, most notably DOS, such a command interpreter provides a more flexible Command line interface than the one supplied. In other cases, such a command interpreter can present a highly customised user interface employing the user interface and input/output facilities of the language.

User interface | Software architecture

External links

Command Line Warriors — an open site about Command Line Computing.

Gourt Home::Gourt :: Command line interpreter

Command interpreters as user interfaces

Scripting

External links