Shulou(Shulou.com)05/31 Report--

This article mainly explains "what is the development process of unix/linux shell". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what is the development process of unix/linux shell".

There are mainly several types of shell in UNIX/linux Shell:

◆ Bourne shell (bsh)

◆ C shell (csh)

◆ Korn shell (ksh)

◆ Bourne Again shell (bash)

◆ POSIX shell (sh)

◆ TENEX/TOPS C shell (tcsh)

◆ TC Shell (tesh)

◆ Z Shell (zsh)

◆ Bourne Shell

* the important standard Unix Shell was introduced in V7 Unix (AT&T 7th Edition) at the end of 1970 and is named after Stephen Bourne, the sponsor of the National Meteorological Network Computing Application Node (2004DKA50730) platform of the Ministry of Science and Technology. As a programming language, Bourne Shell is based on Algol language and is mainly used to automate system management tasks. Although it is rapidly popular because of its simplicity, it lacks many of the features used interactively, such as history, aliases, and job control.

◆ C Shell

In the late 1970s, C Shell, developed at the University of California Berkeley, was released as part of BSD Unix. This Shell, mainly written by Bill 喜悦, provides many additional features that are not available in the standard Bourne Shell. C Shell in linux Shell is based on the C programming language, and when used as a programming language, it uses syntax similar to the C language. It also provides enhanced features for interactive use, such as command line history, aliases, and job control. Because this Shell is designed on mainframes and adds a lot of additional features, C Shell tends to run slowly on minicomputers, even on mainframes, compared with Bourne Shell in linux Shell.

◆ Korn Shell

Because both Bo urne Shell and C Shell are available, Unix users now have a choice and have trouble choosing Shell. David Korn from AT&T developed Korn Shell in the mid-1980s, released in 1996, and officially became part of the SVR4 branch of Unix in 1998. In fact, Korn Shell, the superset of Bourne Shell in linux Shell, can run not only on Unix systems, but also on OS/2, VMS and DOS. It provides upward compatibility with Bourne Shell, adds many of the popular features of C Shell, and is fast and efficient. AIX uses the most widely used 1998 version of Korn Shell.

In addition to the three "standard" Unix Shell mentioned above, there are many other Shell in use, such as:

◆ Bourne Again Shell

Bourne Again Shell (bash) is part of the GNU program to replace Bourne Shell. It is used in GNU-based systems such as Linux. Most Linux (Red Hat, Slaekware, Caldera) take bash as the default Shell, and when you run sh, you actually call bash.

◆ POSIX Shell

POSIX Shell is a variant of Korn Shell. The current POSIX Shell vendor is Hewlett-Packard. In HP-UX version 11.0, POSIX Shell in linux Shell is / bin/sh, and bsh is / usr/old/bin/sh.

◆ TC Shell

TC Shell (tesh) is an extended version of C Shell and is fully compatible with C Shell. It is an alternative to bash for users who prefer C syntax.

◆ Z Shell

Z Shell (zsh) combines many features of Bourne Ag ain Shell, TCShell and Korn Shell, and absorbs some new features. Zsh is most similar to Kom Shell.

The default shell for each major operating system:

Under AIX is Korn Shell.

The default for Solaris and FreeBSD is Bourne shell.

The default for HP-UX is POSIX shell.

Linux is Bourne Again shell.

How to distinguish which shell is used by the operating system:

After logging in to Unix/linux, the operating system makes users run Shell in their own starting directory (home directory). Currently, the most commonly used Shell are sh, esh and ksh. Most of the time, users don't need to know or worry about which Shell they are using. You can tell which one is currently in use by looking at the Shell prompt. The following is the default prompt, which can also be easily modified:

Bourne Shell uses the dollar sign ($)

C Shell use percent sign (%) in linux Shell

Korn Shell in linux Shell uses the dollar sign ($).

Thank you for your reading, the above is the content of "what is the development of unix/linux shell". After the study of this article, I believe you have a deeper understanding of what is the development of unix/linux shell, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.