如何将多行值分配给 bash 变量
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How to assign a multiple line value to a bash variable
提问by molecule
I have a variable FOOwith me that needs to be assigned with a value that will be multiple lines. Something like this,
我有一个变量FOO需要分配一个多行的值。像这样的东西，
FOO="This is line 1
This is line 2
This is line 3"
So when I print the value of FOOit should give the following output.
所以当我打印FOO它的值时应该给出以下输出。
echo $FOO
output:
This is line 1
This is line 2
This is line 3
Furthermore, the number of lines will be decided dynamically as I will initialize it using a loop.
此外，行数将动态决定，因为我将使用循环对其进行初始化。
The answers that have been shown in the other question using mainly read -dis not suitable for me as I am doing intensive string operations and the code format is also important.
在另一个问题 using 中显示的答案主要read -d不适合我，因为我正在进行密集的字符串操作，并且代码格式也很重要。
回答by John Kugelman
Don't indent the lines or you'll get extra spaces. Use quotes when you expand "$FOO"to ensure the newlines are preserved.
不要缩进这些行，否则你会得到额外的空格。展开时使用引号"$FOO"以确保保留换行符。
$ FOO="This is line 1
This is line 2
This is line 3"
$ echo "$FOO"
This is line 1
This is line 2
This is line 3
Another way is to use \nescape sequences. They're interpreted inside of $'...'strings.
另一种方法是使用\n转义序列。它们在$'...'字符串内部被解释。
$ FOO=$'This is line 1\nThis is line 2\nThis is line 3'
$ echo "$FOO"
A third way is to store the characters \and n, and then have echo -einterpret the escape sequences. It's a subtle difference. The important part is that \nisn't interpreted inside of regular quotes.
第三种方法是存储字符\和n，然后echo -e解释转义序列。这是一个微妙的区别。重要的部分是它\n没有在常规引号内解释。
$ FOO='This is line 1\nThis is line 2\nThis is line 3'
$ echo -e "$FOO"
This is line 1
This is line 2
This is line 3
You can see the distinction I'm making if you remove the -eoption and have echoprint the raw string without interpreting anything.
如果您删除该-e选项并echo打印原始字符串而不解释任何内容，您可以看到我所做的区别。
$ echo "$FOO"
This is line 1\nThis is line 2\nThis is line 3
回答by Jonny Henly
When you initialize FOOyou should use line breaks: \n.
初始化FOO时应使用换行符：\n.
FOO="This is line 1\nThis is line 2\nThis is line 3"
Then use echo -eto output FOO.
然后用于echo -e输出FOO。
It is important to note that
\ninside"..."is NOT a line break, but literal\, followed by literaln. It is only when interpreted byecho -ethat this literal sequence is converted to a newline character. — wise words from mklement0
需要注意的是，
\ninside"..."不是换行符，而是literal\，后跟literaln。这是仅当由解释echo -e，这种文字序列被转换成一个新行字符。— 来自mklement0 的明智之言
#!/bin/bash
FOO="This is line 1\nThis is line 2\nThis is line 3"
echo -e $FOO
Output:
This is line 1
This is line 2
This is line 3
回答by Chetabahana
You could also store the lines to a variable using read lines:
您还可以使用读取行将行存储到变量中：
$ read -r -d '' FOO << EOF
This is line 1
This is line 2
This is line 3
EOF
To see the newline on printing use quotes around the variable: (echo "$FOO"not echo $FOO)
要查看打印时的换行符，请在变量周围使用引号：（echo "$FOO"不是echo $FOO）
$ echo "$FOO"
This is line 1
This is line 2
This is line 3
