awk 中的 Shell 变量解释错误
在下面的代码中，我尝试将 shell varibale 传递给 awk。但是，当我尝试将其作为 a.sh foo_bar 运行时，打印的输出是“foo is not returned”，而当我将其作为 a.sh bar_bar 运行时，打印的输出是“foo is不稳定”。 awk 有错误还是我在这里做错了什么？
我正在使用 gawk-3.0.3。
#!/bin/awk
model=$1
awk ' {
match("'$model'", /foo/)
ismodel=substr("'$model'", RSTART, RLENGTH)
if ( ismodel != foo ) {
print " foo is not declared"
} else {
print " foo is declared"
}
}
' dummy
dummy 是带有单个空行的文件。
谢谢，
In following code I am trying to pass shell varibale to awk. But when I try to run it as a.sh foo_bar the output printed is "foo is not declared" and when I run it as a.sh bar_bar the output printed is " foo is declared" . Is there a bug in awk or I am doing something wrong here?
I am using gawk-3.0.3.
#!/bin/awk
model=$1
awk ' {
match("'$model'", /foo/)
ismodel=substr("'$model'", RSTART, RLENGTH)
if ( ismodel != foo ) {
print " foo is not declared"
} else {
print " foo is declared"
}
}
' dummy
dummy is file with single blank line.
Thanks,
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评论（3）
您应该使用 AWK 的变量传递而不是复杂的引用：
您的脚本是作为 shell 脚本编写的，但您有一个 AWK shebang 行。您可以将其更改为
#!/bin/sh。You should use AWK's variable passing instead of complex quoting:
Your script is written as a shell script, but you have an AWK shebang line. You could change that to
#!/bin/sh.这不是错误，而是代码中的错误。有问题的行是：
这里
foo应该是"foo"。现在您正在与一个空变量进行比较。当您有匹配项时，此值为 false；当您没有匹配项时，此值为 true。所以问题不在于你使用 shell 变量的方式。但正如其他回答者所说，将参数传递给 awk 的首选方法是使用 -v 开关。当您决定将 awk 脚本放在单独的文件中并防止所有类型的引用问题时，这也将起作用。
我也不确定您对虚拟文件的使用情况。这只是为了举例吗？否则，您应该省略该文件并将所有代码放入
BEGIN {}块中。This is not a bug, but an error in your code. The problematic line is:
Here
fooshould be"foo". Right now you are comparing with an empty variable. This gives false when you have a match, and true when you have no match. So the problem is not the way you use the shell variables.But as the other answerers have said, the preferred way of passing arguments to
awkis by using the-vswitch. This will also work when you decide to put your awk script in a separate file and prevents all kind of quoting issues.I'm also not sure about your usage of a dummy file. Is this just for the example? Otherwise you should omit the file and put all your code in the
BEGIN {}block.使用 -v 选项从 shell 传入变量
use -v option to pass in variable from the shell