检查一个数字是否等于bash中的另一个数字

问题描述

我一直在尝试比较Bash中的两个数字是否相等(如果相等，则打印一条消息)，但是对于这个简单的程序，我却收到了一些奇怪的错误消息:

I've been trying to compare whether two numbers in Bash are equal (and print a message if they are equal), but I'm getting some strange error messages for this simple program:

#!/bin/bash

fun2 (){
    $x = 3
    //#prog.sh: line 4: =: command not found
    if [x == 3]
        then
    //#prog.sh: line 6: [x: command not found
            echo "It's 3!"
    fi
}
fun2

相应的错误显示在导致这些错误的行下方.

The corresponding errors are shown below the lines that caused those errors.

推荐答案

必须为:

 if [ $x -eq 3 ]; then .....

如果您希望使用更具可读性和自我解释性的代码，请使用以下语法:

if you prefer a more readable and self-explanatory code, use this syntax:

 if test $x -eq 3; then .....

说明:

要比较整数，必须使用这些运算符(从man测试复制):

To compare integers you must use those operators (copied from man test):

   INTEGER1 -eq INTEGER2
          INTEGER1 is equal to INTEGER2

   INTEGER1 -ge INTEGER2
          INTEGER1 is greater than or equal to INTEGER2

   INTEGER1 -gt INTEGER2
          INTEGER1 is greater than INTEGER2

   INTEGER1 -le INTEGER2
          INTEGER1 is less than or equal to INTEGER2

   INTEGER1 -lt INTEGER2
          INTEGER1 is less than INTEGER2

   INTEGER1 -ne INTEGER2
          INTEGER1 is not equal to INTEGER2

运算符==和！=仅用于字符串比较.

operators == and != are for string comparison only.

有关信息:"["命令是系统"test"命令的别名.

for information: "[" command is an alias for system "test" command.

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