linux--Introduction to Shell

Here is a summary of some of the recent learning shell knowledge points
Blog Park-Bang Bang sauce Good * * *

1. What is a shell
(1) The shell communicates the instructions we enter with kernel so that kernel can control the Jiyu hardware to work correctly and without errors.
(2) We always need to let the user operating system, so there is the application developed on the operating system! Users can
Use the program to command the core and let the core achieve the hardware tasks we need. The application is actually at the very outside of the office, just like the shell of an egg, so this is called the Shell program (shell).
(3) Including man, chmod, Chown, VI, Fdisk, MKFS, and so on, these instructions are standalone applications, and we can manipulate these applications through shell programs (that is, instruction-column mode) to let these applications call the core to operate the required work.

The history of 2.shell
Due to the early years of the UNIX era, the development of many, so because the SHell according to the development of the different version of the Bourne, such as the often heard of the shell (SH), in the sun in the pre-C shell, the commercially used K shell, and tcsh, and so on, each shell
Each has its own characteristics.

Shell's simple history: the first popular shell was developed by Steven Bourne, to commemorate him, so called the Bourne shell, or directly referred to as sh! And then another widely-circulated shell was a shell from Berkeley's Bill Joy, which was designed to be attached to the BSD version of Unix, a shell that was a bit like the C language, so it was named C Shell, short for csh!. Because Sun hosts are quite large in academia, and sun is one of the BSD branches, the C shell is another important and widely circulated shell.

3. The shell of the system
View the shell:cat/etc/shells of the system
/bin/sh (has been replaced by/bin/bash)
/bin/bash (which is the Linux preset shell)
/bin/ksh (KornShell by T-Bell Lab. Developed, compatible with bash)
/BIN/TCSH (Consolidated C Shell, provides more features)
/BIN/CSH (has been replaced by/BIN/TCSH)
/bin/zsh (based on Ksh developed, more powerful shell)

4.bash Shell features
(1) Order editing ability History
(2) command and file Completion function Tab key
(3) Command alias setting function
(4) Work control, foreground background control
(5) Programmatic scripting
(6) wildcard characters

linux--Introduction to Shell