Linux Commands for Beginners--Arithmetic in Bash--expr,let commands

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于 2013-09-03 17:10:42 发布

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本文链接：https://blog.youkuaiyun.com/piniheaven/article/details/11002711

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本文介绍了如何在Bash中进行基本的算术运算，包括加、减、乘、除等操作，并通过示例展示了使用`expr`命令和`let`关键字的方法。

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In this part,I will show you how to do some arithmetic calculation in Bash.

1.COMMAND:
      expr
DESCRIPTION:
       Print the value of EXPRESSION to standard output.
SYNOPSIS:
       expr EXPRESSION

Example:
root@piniheaven:~# expr 1 + 1
2
root@piniheaven:~# expr 2 - 1
1
root@piniheaven:~# expr 4 / 2
2
root@piniheaven:~# expr 2 \* 2 #Tip: when you want to do some multiplication,you should use backslash
4

2.COMMAND:
     let
DESCRIPTION:
     carry out arithmetic operations on variables.

Example:
root@piniheaven:~# let " val=(1+1)*2" # will compute 2 times 2 and assign the result to the variable "val".
root@piniheaven:~# echo $val    #print variable val
4