what is linux tcl

In Linux, the full name of tcl is "Tool Command Language", which means "tool command language". It is a string-based command language and an interpreted language; TCL is often used for rapid prototyping. Aspects such as development, scripting, GUI and testing.

#The operating environment of this tutorial: linux5.9.8 system, Dell G3 computer.

What is Tcl?

Tcl (Tool Command Language) is a scripting language, a string-based command language, and an interpreted language. The so-called interpretability means that unlike other high-level languages ​​that require compilation and connection, like other Shell languages, each statement is directly interpreted and executed sequentially;

TCL was originally on the Unix platform. Later ported to Windows, DOS, OS/2 and Mac OSX. TCL is very similar to other UNIX shell languages, such as the Bourne Shell (Sh), the C Shell (csh), the Korn Shell (sh), and Perl.

Its purpose is to provide programs with the ability to interact with other programs and also to act as an embeddable translator. Although the original purpose was to enable programs to interact, it is possible to find fully fledged applications written in Tcl/Tk.

TCL is often used for rapid prototyping, scripting, GUI and testing.

Tcl actually consists of two parts: a language and a library.

• First of all, Tcl is a simple scripting language, mainly used to issue commands to interactive programs such as text editors, debuggers and shells. It has a simple syntax and is highly extensible. Tcl can create new procedures to enhance the capabilities of its built-in commands.

• Secondly, Tcl is a library package that can be embedded in applications. The Tcl library contains a parser, routines for executing built-in commands and allows you to extend ( library functions that define new procedures).

  The application can generate and execute Tcl commands. The commands can be generated by the user or read from an input in the user interface (button or menu, etc.). However, after receiving the command, the Tcl library decomposes it and executes the built-in command, which often results in recursive calls.

Tcl data types are simple. For Tcl, there is only one type of data it has to process - strings. Tcl stores variable values ​​as strings, regardless of their actual type. The built-in Tk (toolkit) graphics tool can provide simple and rich graphics functions, allowing users to easily create simple graphical interfaces.

The execution of Tcl is interactive. Tcl provides an interactive command interface. There are two interfaces: tclsh and wish. tclsh only supports Tcl commands, while wish supports Tcl and Tk commands. Through the interactive interface, we can execute the commands one by one just like executing UNIX shell commands and get the execution results immediately.

Tcl/Tk can provide cross-platform support. Tcl language can run on most of today's popular UNIX, WINDOWS and Macintosh systems, and the commands are common, but the startup details are slightly different.

The features of Tcl include:

* Everything is a command, including syntax structures (for, if, etc.).

　* Everything can be redefined and overloaded.

　* All data types can be regarded as strings.

* The syntax rules are quite simple

* Provide event drivers for Sockets and files. Time-based or user-defined events are also possible.

　* Dynamic domain definition.

　* Easily extendable in C, C, or Java.

　* Interpreted language, code can be changed dynamically.

　* Full Unicode support.

　* Platform independent. It can run on Win32, UNIX, and Mac.

　* Tightly integrated with Windows GUI.

　* The code is compact and easy to maintain.

TCL itself does not provide object-oriented support. But the language itself is easily extended to support object orientation. Many C language extensions provide object-oriented capabilities, including XOTcl, Incr Tcl, etc. In addition, the SNIT extension itself is written in TCL.

The most widely used TCL extension is TK. TK provides graphical user interface GUI under various OS platforms. Even the powerful Python language does not provide its own GUI alone, but provides interfaces to adapt to TK. Another popular extension package is Expect. Expect provides the ability to automatically execute commands through the terminal, such as (passwd, ftp, telnet and other command-driven shells).

Tcl is widely used as a script language. In most cases, Tcl and the Tk ("Tool Kit") library are used together. Tk is a series of commands and procedures that make Tcl easy to write graphical user interfaces.

An important feature of Tcl is its extensibility. If a program needs to use some functions that are not provided by standard Tcl, you can use the c language to create some new Tcl commands and easily integrate them. Precisely because Tcl is easy to extend, many people have written extension packages for it and shared them online.

Tcl is different from other programming languages ​​such as c. It is an interpreted language rather than a compiled language. A Tcl program consists of a series of Tcl commands, which are interpreted and run by the Tcl interpreter at runtime. One advantage of the interpreted run is that it can generate Tcl script for itself.

Most of Tcl's input/output is done through puts and gets. The Puts command is displayed on the console, and the gets command obtains data from the console input and stores it in a variable.

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