Linux 如何使用带有变量的 Bash 编写多行字符串？
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How to write multiple line string using Bash with variables?
提问by
How can I write multi-lines in a file called myconfig.confusing BASH?
如何在myconfig.conf使用 BASH调用的文件中编写多行？
#!/bin/bash
kernel="2.6.39";
distro="xyz";
echo <<< EOL
line 1, ${kernel}
line 2,
line 3, ${distro}
line 4
line ...
EOL >> /etc/myconfig.conf;
cat /etc/myconfig.conf;
采纳答案by ktf
The syntax (<<<) and the command used (echo) is wrong.
语法 ( <<<) 和使用的命令 ( echo) 是错误的。
Correct would be:
正确的应该是：
#!/bin/bash
kernel="2.6.39"
distro="xyz"
cat >/etc/myconfig.conf <<EOL
line 1, ${kernel}
line 2,
line 3, ${distro}
line 4 line
...
EOL
cat /etc/myconfig.conf
This construction is referred to as a Here Documentand can be found in the Bash man pages under man --pager='less -p "\s*Here Documents"' bash.
这种结构被称为Here Document，可以在 Bash 手册页中找到man --pager='less -p "\s*Here Documents"' bash。
回答by Kent
#!/bin/bash
kernel="2.6.39";
distro="xyz";
cat > /etc/myconfig.conf << EOL
line 1, ${kernel}
line 2,
line 3, ${distro}
line 4
line ...
EOL
this does what you want.
这做你想要的。
回答by William Pursell
The heredoc solutions are certainly the most common way to do this. Other common solutions are:
Heredoc 解决方案当然是最常用的方法。其他常见的解决方案是：
echo 'line 1, '"${kernel}"'
line 2,
line 3, '"${distro}"'
line 4' > /etc/myconfig.conf
and
和
exec 3>&1 # Save current stdout
exec > /etc/myconfig.conf
echo line 1, ${kernel}
echo line 2,
echo line 3, ${distro}
...
exec 1>&3 # Restore stdout
回答by Tk421
If you do not want variables to be replaced, you need to surround EOL with single quotes.
如果不想替换变量，则需要用单引号将 EOL 括起来。
cat >/tmp/myconfig.conf <<'EOL'
line 1, ${kernel}
line 2,
line 3, ${distro}
line 4 line
...
EOL
Previous example:
上一个例子：
$ cat /tmp/myconfig.conf
line 1, ${kernel}
line 2,
line 3, ${distro}
line 4 line
...
回答by rashok
Below mechanism helps in redirecting multiple lines to file. Keep complete string under "so that we can redirect values of the variable.
下面的机制有助于将多行重定向到文件。保留完整的字符串，"以便我们可以重定向变量的值。
#!/bin/bash
kernel="2.6.39"
echo "line 1, ${kernel}
line 2," > a.txt
echo 'line 2, ${kernel}
line 2,' > b.txt
Content of a.txtis
的内容a.txt是
line 1, 2.6.39
line 2,
Content of b.txtis
的内容b.txt是
line 2, ${kernel}
line 2,
