为什么它说整数预期？ [复制]

Question

#!/bin/bash

if [ "$1" == "" ] || [ "$2" == "" ] || [ "$3" == "" ]
    then
    echo This is empty or does not have all 3 parameters
    exit
elif [ "$1" -lt 0 ]
    then
    echo This aint a number
    exit

fi

尝试运行脚本，假设首先检查是否输入了 3 个位置参数， 其次检查输入是否为数字，然后显示最大的。我得到了第一个 if 语句，但是当我为第一个参数输入一个字符串来测试 elif 语句时，出现一个错误，表明需要整数。

Answer 1

你必须检查正则表达式来检查字符串是否只包含数字，但你可以试试这个：

#!/bin/bash

if [[ "$1" == "" ]] || [[ "$2" == "" ]] || [[ "$3" == "" ]]
    then
    echo "This is empty or does not have all 3 parameters"
    exit
elif ! [[ "$1" =~ ^[0-9]+$ ]]
    then
    echo "This aint a number"
    exit

fi

请注意，[[ 实际上是一个返回 0（真）或 1（假）的命令/程序。任何遵循相同逻辑的程序（如所有基本工具，如 grep(1) 或 ping(1)）都可以用作条件：

[[ -z STRING ]] #Empty string
[[ -n STRING ]] #Not empty string
[[ STRING == STRING ]]  #Equal
[[ STRING != STRING ]]  #Not Equal
[[ NUM -eq NUM ]]   #Equal
[[ NUM -ne NUM ]]   #Not equal
[[ NUM -lt NUM ]]   #Less than
[[ NUM -le NUM ]]   #Less than or equal
[[ NUM -gt NUM ]]   #Greater than
[[ NUM -ge NUM ]]   #Greater than or equal
[[ STRING =~ STRING ]]  #Regexp
(( NUM < NUM )) #Numeric conditions

还检查字符串是否仅包含数字/数字字符

[[ "$1" =~ ^[0-9]+$ ]]

Answer 2

请使用正则表达式检查号码

#!/bin/bash
if [ $1 == "" ] || [ $2 == "" ] || [ $3 == "" ]
    then
    echo This is empty or does not have all 3 parameters
    exit
elif ! [[ $1 =~ ^[0-9]+$ ]]
    then
    echo This aint a number
    exit

fi