linux命令：浅谈shell中如何进行算术运算

1、let 算术运算表达式

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、$[算术运算表达式]

       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、$((算术运算表达式))

       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 算术运算表达式，表达式中各操作数及运算符之间要有空格，而且要使用命令引用

       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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