echo '1 2'|awk "{print $2}"的输出为什么是 1 2

[freemoon]

awk 的语句改为双引号就变成了整行输出，双引号起了什么作用？请教==

[ynyounuo]

awk "{print \$2}"

https://www.gnu.org/software/bash/manual/html_node/Quoting.html#Quoting

[ynyounuo]

Also
https://www.gnu.org/software/gawk/manual/html_node/Quoting.html

[ynyounuo]

> Double quotes protect most things between the opening and closing quotes. The shell does at least variable and command substitution on the quoted text. Different shells may do additional kinds of processing on double-quoted text.
> Because certain characters within double-quoted text are processed by the shell, they must be escaped within the text. Of note are the characters ‘$’, ‘`’, ‘\’, and ‘"’, all of which must be preceded by a backslash within double-quoted text if they are to be passed on literally to the program.

[widewing]

shell $2=空字符串

[freemoon]

@ynyounuo 按文档的意思双引号就是保护了`$`，这里就变成了纯文本的 print $2，那么为什么会输出 1 2 呢？

[sakuramanstein]

看了一下楼上的答案，是不是这个意思 双引号内的字符串先由 shell 解析 于是$2 被解析为空(没有这个变量)，等价于 awk "{print}"，所以输出 1 2 。

[freemoon]

@widewing 行，大概明白了，我试了一下 awk 中没办法打印出文本的$，这个符号一定会被处理，只是处理方式不同

[tlday]

echo '1 2'|awk '{print $2}'

[freemoon]

@sakuramanstein 应该是这样的。但是在 awk 中好像没办法打印出文本的美元符了，通过 echo '$1'是可以的，awk 对单双引号的解释和 echo 对其的处理方式完全是相反的。

[sakuramanstein]

@lasuar 可以啊 awk '{print "$"}'

[freemoon]

@sakuramanstein 好的，3q==

[labulaka521]

awk 请使用单引号