Linux Shell 运算符

概述

在 Linux Shell 中，运算符是用来操作变量和常量的特殊符号。它们提供了一种简洁方便的方式来执行各种算术、逻辑和位运算操作。本文将介绍几种常见的 Linux Shell 运算符和它们的用法。

算术运算符

算术运算符用于执行数学运算，包括加法、减法、乘法和除法等。

1. 加法运算符：+

   num1=10
   num2=5
   sum=$(($num1 + $num2))
   echo "The sum of $num1 and $num2 is: $sum"
   

2. 减法运算符：-

   num1=10
   num2=5
   difference=$(($num1 - $num2))
   echo "The difference between $num1 and $num2 is: $difference"
   

3. 乘法运算符：*

   num1=10
   num2=5
   product=$(($num1 * $num2))
   echo "The product of $num1 and $num2 is: $product"
   

4. 除法运算符：/

   num1=10
   num2=5
   quotient=$(($num1 / $num2))
   echo "The quotient of $num1 divided by $num2 is: $quotient"
   

5. 取余运算符：%

   num1=10
   num2=3
   remainder=$(($num1 % $num2))
   echo "The remainder of $num1 divided by $num2 is: $remainder"
   

逻辑运算符

逻辑运算符用于执行逻辑判断，返回布尔值 true 或 false。

1. 逻辑与运算符：&&

   age=25
   if (($age > 18 && $age < 30)); then
       echo "You are a young adult."
   else
       echo "You are either too young or too old."
   fi
   

2. 逻辑或运算符：||

   day="Saturday"
   if [ $day == "Saturday" ] || [ $day == "Sunday" ]; then
       echo "It's the weekend!"
   else
       echo "It's a weekday."
   fi
   

3. 逻辑非运算符：!

   success=false
   if [ ! $success ]; then
       echo "The operation failed."
   fi
   

比较运算符

比较运算符用于比较两个值之间的关系，返回布尔值 true 或 false。

1. 相等运算符：==

   num1=10
   num2=5
   if [ $num1 == $num2 ]; then
      echo "The numbers are equal."
   else
      echo "The numbers are not equal."
   fi
   

2. 不等运算符：!=

   num1=10
   num2=5
   if [ $num1 != $num2 ]; then
      echo "The numbers are not equal."
   else
      echo "The numbers are equal."
   fi
   

3. 大于运算符：>

   num1=10
   num2=5
   if [ $num1 > $num2 ]; then
      echo "$num1 is greater than $num2."
   else
      echo "$num1 is not greater than $num2."
   fi
   

4. 小于运算符：<

   num1=10
   num2=5
   if [ $num1 < $num2 ]; then
      echo "$num1 is less than $num2."
   else
      echo "$num1 is not less than $num2."
   fi
   

位运算符

位运算符用于对二进制位进行操作。

1. 按位与运算符：&

   num1=5
   num2=3
   result=$(($num1 & $num2))
   echo "The result of bitwise AND between $num1 and $num2 is: $result"
   

2. 按位或运算符：|

   num1=5
   num2=3
   result=$(($num1 | $num2))
   echo "The result of bitwise OR between $num1 and $num2 is: $result"
   

3. 按位异或运算符：^

   num1=5
   num2=3
   result=$(($num1 ^ $num2))
   echo "The result of bitwise XOR between $num1 and $num2 is: $result"
   

4. 按位取反运算符：~

   num1=5
   result=$((~$num1))
   echo "The result of bitwise NOT of $num1 is: $result"
   

总结

Linux Shell 提供了多种运算符来进行算术、逻辑和位运算。在编写 Shell 脚本时，熟练使用这些运算符可以大大提高脚本的灵活性和执行效率。通过本文的介绍，相信读者对 Linux Shell 运算符有了更清楚的理解。祝使用愉快！

本文来自极简博客，作者：奇迹创造者，转载请注明原文链接：Linux Shell 运算符