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This article mainly introduces the relevant knowledge of "what are the characteristics of tcl of linux". The editor shows you the operation process through an actual case, and the method of operation is simple, fast and practical. I hope that this article "what are the characteristics of tcl of linux" can help you solve the problem.

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 interpretive language; TCL is often used in rapid prototyping, 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 interpretive language. Interpretation means that, unlike other high-level languages, it does not need to be compiled and joined, but like other Shell languages, it directly interprets and executes each statement sequentially.

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

Its purpose is to provide the ability for programs to interact with other programs as well as as an embeddable translation. Although the original goal is to enable programs to interact, you can find full-fledged applications written by Tcl/Tk.

TCL is often used in 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 that is mainly used to issue commands to interoperability programs such as text editors, debuggers, and shell. It has a simple syntax and strong extensibility, and Tcl can create new procedures to enhance its built-in command capabilities.

Second, Tcl is a library package that can be embedded in applications, and Tcl's library contains an analyzer, routines for executing built-in commands, and library functions that allow you to extend (define new procedures).

The application can generate and execute Tcl commands, which can be generated by the user or read from an input in the user interface (buttons, menus, etc.). However, when the Tcl library receives the command, it decomposes it and executes the built-in command, often resulting in recursive calls.

The Tcl data type is simple. For Tcl, there is only one kind of data it has to deal with-strings. Tcl stores the value of a variable as a string, regardless of its actual usage type. Embedded Tk (toolkit) graphics tools can provide simple and rich graphics functions, so that users can easily create a simple graphical interface.

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

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

Features of Tcl include:

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

* anything can be redefined and reloaded.

* all data types can be treated as strings.

* the grammar rules are quite simple

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

* dynamic domain definition.

* it's easy to extend with C, Cellular extensions, or Java.

* interpret the language, and the code can be changed dynamically.

* full Unicode support.

* platform independent. You can run on Win32, UNIX and Mac.

* tightly integrated with Windows's GUI.

* Compact code and easy to maintain.

TCL itself does not provide object-oriented support. But the language itself can easily be extended to support object-oriented. Many C language extensions provide object-oriented capabilities, including XOTcl, Incr Tcl and so on. Besides, the SNIT extension itself is written in TCL.

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

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

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

Unlike other programming languages such as c, Tcl is an interpreted language rather than a compiled language. The Tcl program consists of a series of Tcl commands that are interpreted and run by the Tcl interpreter at run time. One of the advantages of interpretive running is that it can generate Tcl script for itself.

The vast majority of Tcl input / output is done through puts and gets. The Puts command is displayed on console, and the gets command takes data from the console input and stores it in a variable.

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