![](https://img.haomeiwen.com/i7870948/c71dd8da557a6fee.png)
1.算数运算符
![](https://img.haomeiwen.com/i7870948/85de1e023c3435f7.png)
![](https://img.haomeiwen.com/i7870948/8290fbe792aab368.png)
![](https://img.haomeiwen.com/i7870948/8b12f93ed6e62007.png)
![](https://img.haomeiwen.com/i7870948/f0d7d5cdad5c27c8.png)
你没有看错。输出的是字符串,而不是2这个数值。
算数运算方式
![](https://img.haomeiwen.com/i7870948/ad891a12c899d6ab.png)
(1)使用$(())
![](https://img.haomeiwen.com/i7870948/af042b213caac765.png)
(2)使用 let命令
![](https://img.haomeiwen.com/i7870948/8a46e56d32ad588d.png)
(3)使用 expr 外部程式
![](https://img.haomeiwen.com/i7870948/6d1955b470c901f1.png)
(4)使用 []
![](https://img.haomeiwen.com/i7870948/fcc5db86abe54504.png)
![](https://img.haomeiwen.com/i7870948/a2b351f7366cf28c.png)
2.关系运算符
![](https://img.haomeiwen.com/i7870948/93ec5c7beda3c4f4.png)
3.布尔运算符
![](https://img.haomeiwen.com/i7870948/6e468d63b5845553.png)
4.逻辑运算符
![](https://img.haomeiwen.com/i7870948/850c8223e6c5744c.png)
5.字符串运算符
![](https://img.haomeiwen.com/i7870948/409cc32c5ef7d2aa.png)
检查2个字符串是否相等
![](https://img.haomeiwen.com/i7870948/7fe76f987c6863c9.png)
![](https://img.haomeiwen.com/i7870948/59531386e47b77a8.png)
检测字符串长度是否为0
![](https://img.haomeiwen.com/i7870948/fea3374872d579ca.png)
![](https://img.haomeiwen.com/i7870948/0f5c9efcbdc2b4c9.png)
检测字符串是否为空
![](https://img.haomeiwen.com/i7870948/605b3cbbf9b55e9d.png)
![](https://img.haomeiwen.com/i7870948/cf6a1c0465d239df.png)
6.文件测试运算符
![](https://img.haomeiwen.com/i7870948/7a43a72d51d9f2a5.png)
![](https://img.haomeiwen.com/i7870948/eccb24ec5aec681d.jpg)
![](https://img.haomeiwen.com/i7870948/9144ba21e39b39b3.jpg)
1.算数运算符
你没有看错。输出的是字符串,而不是2这个数值。
算数运算方式
(1)使用$(())
(2)使用 let命令
(3)使用 expr 外部程式
(4)使用 []
2.关系运算符
3.布尔运算符
4.逻辑运算符
5.字符串运算符
检查2个字符串是否相等
检测字符串长度是否为0
检测字符串是否为空
6.文件测试运算符
本文标题:2.2.4 shell 算数运算符
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