将文本文件的唯一内容与未注册为相等的预期字符串进行比较

Question

我编写了一个 shell 脚本来检查哪些“.err”文本文件为空。有些文件具有特定的重复短语，例如此示例文件fake_error.err（有意使用空行）：

WARNING: reaching max number of iterations

WARNING: reaching max number of iterations

WARNING: reaching max number of iterations

WARNING: reaching max number of iterations

WARNING: reaching max number of iterations

WARNING: reaching max number of iterations

WARNING: reaching max number of iterations

WARNING: reaching max number of iterations

WARNING: reaching max number of iterations

除了空文件之外我还想删除它。我编写了以下脚本来执行此操作

#!/bin/bash

for file in *error.err; do
    if [ ! -s $file ]
    then
        echo "$file is empty"
        rm $file
    else
        # Get the unique, non-blank lines in the file, sorted and ignoring blank space
        lines=$(grep -v "^$" "$file" | sort -bu "$file")
        echo $lines

        EXPECTED="WARNING: reaching max number of iterations"
        echo $EXPECTED

        if [ "$lines" = "$EXPECTED" ]
        then
            # Remove the file that only has iteration warnings
            echo "Found reached max iterations!"
            rm $file
        fi

    fi
done

但是，该脚本在文件上运行时的输出fake_error.err是

WARNING: reaching max number of iterations
WARNING: reaching max number of iterations

来自循环中的两个$echo语句，但文件本身不会被删除，并且"Found reached max iterations!"不会打印字符串。我认为问题出在if [ "$lines" = "$EXPECTED" ]，我尝试使用双括号[[ ]]，==但这些都不起作用。我不知道这两个打印的声明有什么区别。

为什么两个变量不相等？