Linux Command Encyclopedia system settings: Declare

Function Description: Declare &http://www.aliyun.com/zixun/aggregation/37954.html ">nbsp;shell variable."

Syntax: Declare [+/-][rxi][variable name = set value] or declare-f

Supplemental NOTE: Declare is a shell directive that can be used in the first syntax to declare a variable and set the properties of the variable ([Rix] is the property of the variable), which can be used in the second syntax to display the Shell function. Without any arguments, all shell variables and functions will be displayed (the same effect as executing the set instruction).

Parameters：
---"-" can be used to specify the properties of the variable, "+" is to cancel the property set by the variable.
-F displays only functions.
R sets the variable to read-only.
The variables specified by x become environment variables that can be used by programs other than the shell.
I [Set value] can be a numeric value, a string, or an expression.