linux 脚本字符串比较

#!/bin/bash

# 精确匹配
str1="hello"
str2="world"
if [ "$str1" == "$str2" ]; then
    echo "Strings are equal."
else
    echo "Strings are not equal."
fi

# 模式匹配
file="example.txt"
if [[ $file == *.txt ]]; then
    echo "It's a text file."
fi

# 正则表达式匹配
email="user@example.com"
if [[ $email =~ ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$ ]]; then
    echo "Valid email address."
else
    echo "Invalid email address."
fi

# 错误的示例
if [ $str1 = $str2 ]; then
    echo "Strings are equal."
fi

# 正确的示例
if [[ $str1 == "$str2" ]]; then
    echo "Strings are equal."
fi

# 错误的正则表达式
if [[ $email =~ ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,} ]]; then
    echo "Valid email address."
fi

# 正确的正则表达式
if [[ $email =~ ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$ ]]; then
    echo "Valid email address."
fi