Use of variables in the shell

1. Declaration of variables

Name= "Blacksonny"

　Note://variable definition does not add $, the variable and equal sign cannot have spaces between

Variable naming rules:

• The first character must be a letter (a-z,a-z).
• You can use an underscore (_) without spaces in the middle.
• Punctuation cannot be used.
• You can't use the keywords in bash (you can see the reserved keywords with the help command)

2. Using variables

If you want to use a variable, add $ to it before the variable, and we recommend using ${name}

such as: $name

1 #!/bin/bash2#description: Use variable3#Author: Blacksonny 4 #Copyright (c) 5 #Script follows here: 6 7 name="blacksonny"8echo  $name  9echo ${name}

The above code then outputs Blacksonny at the same time, where {} is optional and is generally used to define the bounds of the variable

The following code distinguishes between variables and programm, and no person can get the value of a variable

 for inch Java Php Android IOS  do    Echo " I'll study ${book}programm "  Done

3, the variable is redefined, the shell allows to redefine the variable, as with the method of defining the variable, just re-assign the original variable value can be

4. read-only variables

Define a read-only variable by using the ReadOnly keyword

number=1323readonly numbernumber=1333

The run var.sh result is: "./var.sh: Line 24:number: read-only variable", prompting that this variable is not allowed to be modified.

5. Delete variables

Use unset var_name to delete variables

6. Variable type

1) Local Variables

2) Environment variables

3) Shell variables

Use of variables in the shell