Linux commands: Talking about how to perform arithmetic operations in the shell

1 , let arithmetic op-expression

Let c= $A + $B

Eg:a=3 b=5 let c= $A + $B

Echo $C

[Email protected] test]# a=3

[Email protected] test]# b=3

[[email protected] test]# let c= $A + $B

[Email protected] test]# echo $C

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2 , $[arithmetic operation expression]

c=$[$A + $B]

eg:a=2 b=6 c=$[$A + $B]

Echo $C

[Email protected] test]# a=2

[Email protected] test]# b=6

[Email protected] test]# c=$[$A + $B]

[Email protected] test]# echo $C

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3 , $ ((arithmetic expression))

c=$ (($A + $B))

Eg:a=6 b=7 c=$ (($A + $B))

Echo $C

[Email protected] test]# a=6

[Email protected] test]# b=7

[[email protected] test]# c=$ (($A + $B))

[Email protected] test]# echo $C

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4 , expr arithmetic expression, a space between operands and operators in an expression, and a command reference

c= ' expr $A + $B '

eg:a=5 b=6 c= ' expr $A + $B '

Echo $C

[Email protected] test]# a=5

[Email protected] test]# b=6

[[email protected] test]# c= ' expr $A + $B '

[Email protected] test]# echo $C

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Linux commands: Talking about how to perform arithmetic operations in the shell