庆典：读线和保持空间 [英] bash: read line and keep spaces

问题描述

我试图读取包含多个行的文件行。我想确定只包含空格线。
根据定义，一个空行是空的，不包含任何（包括空格）。
我想要检测，这似乎是空行，但他们没有。

I am trying to read lines from a file containing multiple lines. I want to identify lines that contain only spaces. By definition, an empty line is empty and does not contain anything (including spaces). I want to detect lines that seems to be empty but they are not (lines that contain spaces only)

    while read line; do
        if [[ `echo "$line" | wc -w` == 0 && `echo "$line" | wc -c` > 1 ]];
        then
             echo "Fake empty line detected"
        fi
    done < "$1"

但由于读忽略空格开始和在一个字符串的结尾我的code是行不通的。

But because read ignores spaces in the start and in the end of a string my code isn't working.

的文件的一个例子

hi
 hi
(empty line, no spaces or any other char)
hi
  (two spaces)
hey

请帮我修复code

推荐答案

通过清除的 IFS （内部字段分隔符）：

Disable word splitting by clearing the value of IFS (the internal field separator):

while IFS= read -r line; do
....
done < "$1"

的 -r 不是绝对必要的，但它是很好的做法。

The -r isn't strictly necessary, but it is good practice.

另外，一个更简单的方法来检查 行（我假设你在寻找什么也没有，但空白行）的值：

Also, a simpler way to check the value of line (I assume you're looking for a line with nothing but whitespace):

if [[ $line =~ ^$ ]]; then
    echo "Fake empty line detected"
fi

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