Variable names can only contain numbers, letters, and underscores, because some variables that contain other characters have special meanings, and such variables are called special variables.For example, $ represents the ID of the current shell
Common shell: -------------- from "laruence's Linux private dish"
In the early UNIX era, there were many developers, so shell had many versions based on the developer's differences, such
Frequently heard Bourne shell (SH ),C shell,Commonly used
Any shell script you run has access to (inherits) the environment variables accessible to its parent shell. in addition, any arguments you type after the Script Name on the shell command line are passed to the script as a series of variables.
The
[This is my own study notes, welcome reprint, but please specify the source:http://blog.csdn.net/jesson20121020]
Take a look at some of the variables in the shell today.
Variable Type:There are several variables in the shell:1) Local
Create a scriptThere are many different shells in Linux, but usually we use Bash (Bourne again shell) for Shell programming because bash is free and easy to use. So the script I've provided in this article is all about using bash (but in most cases
I. Basic Shell syntax1. VariablesBy convention, Shell variables are composed of uppercase letters and underscores (_). There are two types of Shell variables:Environment VariableEnvironment variables can be transmitted from the parent process to the
Turn from: The world of the Intelligence ReporterThis article combines a number of examples to illustrate how to write a shell script.Why Shell ProgrammingIn Linux systems, although there are a variety of graphical interface tools, sell is still a
1. Linux Scripting Basics
1.1 Basic Introduction to grammar
1.1.1 Start
The program must start with the following line (must be on the first line of the file):
#!/bin/sh
The symbolic #! is used to tell the system that the parameters behind it
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