反斜线GAWK领域 [英] backslash in gawk fields

问题描述

我刚刚被拍成检查与GAWK我所有的输出文件，我作为避免尽我所能。
如何

I've just been made into checking all my output files with gawk which I avoid as much as I can. How does

gawk 'NF \!= 6' file

从

gawk 'NF != 6' file 

这就是，如何反斜杠改变这种前pression意思？

that is, how does the backslash change the meaning of this expression?

应该把它输出线比6不同领域的数量和反斜线结束？

Should it output lines with number of fields different than 6 and ending with backslash?

我收到以下错误在我的文件：

I'm getting the following error on my files:

gawk:    ^ backslash not last character on line

别人吗？

推荐答案

如果您使用双引号代替单引号，然后！是一个特殊字符，应进行转义反斜杠。重要的是，你在逃避感叹号让你的壳的没有看到它。

If you use double quotes instead of single quotes then ! is a special character and should be escaped with a backslash. Importantly, you are escaping the exclamation point so that your shell does not see it.

gawk "NF \!= 6" file

在双引号外壳将转换 \\！到！传递给呆呆地看着前面的参数。反斜杠由gawk的调用时间了。

Within double quotes the shell will convert \! to ! before passing the argument to gawk. The backslash is gone by the time gawk is invoked.

通过单一qutoes，虽然外壳会忽略！字符，所以没有必要用反斜杠转义。事实上，当你发现这是一个语法错误这样做，因为反斜线最终被传递到呆子，这barfs的意外 \\ 。

With single qutoes, though, the shell will ignore ! characters, so there's no need to escape them with backslashes. In fact, as you found out it is a syntax error to do so since the backslash ends up being passed to gawk, which barfs on the unexpected \.

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