带额外空格的多行字符串(保留缩进) [英] Multi-line string with extra space (preserved indentation)

问题描述

我想用以下内容将一些预定义的文本写入文件:

I want to write some pre-defined texts to a file with the following:

text="this is line one

this is line two

this is line three"

echo -e $text > filename

我期待这样的事情:

this is line one
this is line two
this is line three

但是得到了这个:

this is line one
 this is line two
 this is line three

我肯定每个 后面没有空格，但是多余的空格是怎么出来的?

I'm positive that there is no space after each , but how does the extra space come out?

推荐答案

Heredoc 听起来更方便.它用于向ex 或cat

Heredoc sounds more convenient for this purpose. It is used to send multiple commands to a command interpreter program like ex or cat

cat << EndOfMessage
This is line 1.
This is line 2.
Line 3.
EndOfMessage

<<< 后面的字符串表示停止的位置.

The string after << indicates where to stop.

要将这些行发送到文件，请使用:

To send these lines to a file, use:

cat > $FILE <<- EOM
Line 1.
Line 2.
EOM

您也可以将这些行存储到变量中:

You could also store these lines to a variable:

read -r -d '' VAR << EOM
This is line 1.
This is line 2.
Line 3.
EOM

这会将行存储到名为 VAR 的变量中.

This stores the lines to the variable named VAR.

打印时，请记住变量周围的引号，否则您将看不到换行符.

When printing, remember the quotes around the variable otherwise you won't see the newline characters.

echo "$VAR"

更好的是，您可以使用缩进使其在您的代码中更加突出.这次只需在 << 后面添加一个 - 来阻止标签出现.

Even better, you can use indentation to make it stand out more in your code. This time just add a - after << to stop the tabs from appearing.

read -r -d '' VAR <<- EOM
    This is line 1.
    This is line 2.
    Line 3.
EOM

但是你必须在代码中使用制表符而不是空格来缩进.

But then you must use tabs, not spaces, for indentation in your code.

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