Shell Simple usage note (Shell numeric operations) two

The value of the variable in the shell, if you do not specify the type manually, the default is the string type:

For example:

A=123b=456C= $a +#becho $c

The result is output: 123+456

In the shell, if you want to perform numeric operations, you can do this by:

Method 1:

A=123b=456C=$ (($a + $b))

Method 2:

A=123b=456declare-i C= $a + $b

The value type of C is declared by Declare-i to be of type int

Method 3:

A=123b=456C=$ (expr $a + $b) Note that there are spaces on both sides of the + sign

Add and subtract strings by using the Marten expr command

Shell Simple usage note (Shell numeric operations) two