bash 如何在 awk 脚本中使用 shell 变量？

How do I use shell variables in an awk script?

提问by hqjma

I found some ways to pass external shell variables to an awkscript, but I'm confused about 'and ".

我找到了一些将外部 shell 变量传递给awk脚本的方法，但我对'和感到困惑"。

First, I tried with a shell script:

首先，我尝试使用 shell 脚本：

$ v=123test
$ echo $v
123test
$ echo "$v"
123test

Then tried awk:

然后尝试awk：

$ awk 'BEGIN{print "'$v'"}'
$ 123test
$ awk 'BEGIN{print '"$v"'}'
$ 123

Why is the difference?

为什么有区别？

Lastly I tried this:

最后我试过这个：

$ awk 'BEGIN{print " '$v' "}'
$  123test
$ awk 'BEGIN{print ' "$v" '}'
awk: cmd. line:1: BEGIN{print
awk: cmd. line:1:             ^ unexpected newline or end of string 

I'm confused about this.

我对此感到困惑。

回答by Jotne

Getting shell variables into awk

may be done in several ways. Some are better than others. This should cover most of them. If you have a comment, please leave below.????????????????????????????????????????????????????????????????????????????????????v1.5

获取shell变量 awk

可以通过多种方式完成。有些比其他的要好。这应该涵盖其中的大部分。如果您有意见，请在下方留言。?????????????????????????????????????????? ????????????????????????????????????????????????v1.5

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Using -v(The best way, most portable)

使用-v（最好的方式，最便携）

Use the -voption: (P.S. use a space after -vor it will be less portable. E.g., awk -v var=not awk -vvar=)

使用-v选项：（PS 在后面使用一个空格，-v否则便携性会降低。例如，awk -v var=不是awk -vvar=）

variable="line one\nline two"
awk -v var="$variable" 'BEGIN {print var}'
line one
line two

This should be compatible with most awk, and the variable is available in the BEGINblock as well:

这应该与 most 兼容awk，并且该变量也在BEGIN块中可用：

If you have multiple variables:

如果您有多个变量：

awk -v a="$var1" -v b="$var2" 'BEGIN {print a,b}'

Warning. As Ed Morton writes, escape sequences will be interpreted so \tbecomes a real taband not \tif that is what you search for. Can be solved by using ENVIRON[]or access it via ARGV[]

警告。正如 Ed Morton 所写，转义序列将被解释\t为真实的tab，\t如果那是您搜索的内容，则不会。可以通过使用ENVIRON[]或访问它来解决ARGV[]

PSIf you like three vertical bar as separator |||, it can't be escaped, so use -F"[|][|][|]"

PS如果你喜欢三个竖线作为分隔符|||，它不能被转义，所以使用-F"[|][|][|]"

Example on getting data from a program/function inn to awk(here date is used)

从程序/函数客栈获取数据的示例awk（此处使用日期）

awk -v time="$(date +"%F %H:%M" -d '-1 minute')" 'BEGIN {print time}'

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Variable after code block

代码块后的变量

Here we get the variable after the awkcode. This will work fine as long as you do not need the variable in the BEGINblock:

这里我们得到awk代码后面的变量。只要您不需要BEGIN块中的变量，这将正常工作：

variable="line one\nline two"
echo "input data" | awk '{print var}' var="${variable}"
or
awk '{print var}' var="${variable}" file

• Adding multiple variables:

• 添加多个变量：

awk '{print a,b,$0}' a="$var1" b="$var2" file

awk '{print a,b,$0}' a="$var1" b="$var2" file

• In this way we can also set different Field Separator FSfor each file.

• 这样我们也可以FS为每个文件设置不同的字段分隔符。

awk 'some code' FS=',' file1.txt FS=';' file2.ext

awk 'some code' FS=',' file1.txt FS=';' file2.ext

• Variable after the code block will not work for the BEGINblock:

• 代码块之后的变量将不适用于该BEGIN块：

echo "input data" | awk 'BEGIN {print var}' var="${variable}"

echo "input data" | awk 'BEGIN {print var}' var="${variable}"

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Here-string

这里字符串

Variable can also be added to awkusing a here-stringfrom shells that support them (including Bash):

还可以添加变量以awk使用支持它们的 shell（包括 Bash）中的here-string：

awk '{print 
printf '%s' "$variable" | awk '{print 
X=MyVar
awk 'BEGIN{print ENVIRON["X"],ENVIRON["SHELL"]}'
MyVar /bin/bash
}'
}' <<< "$variable"
test

This is the same as:

这与：

v="my data"
awk 'BEGIN {print ARGV[1]}' "$v"
my data

P.S. this treats the variable as a file input.

PS 这将变量视为文件输入。

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ENVIRONinput

ENVIRON输入

As TrueY writes, you can use the ENVIRONto print Environment Variables. Setting a variable before running AWK, you can print it out like this:

正如 TrueY 所写，您可以使用ENVIRON来打印Environment Variables。在运行 AWK 之前设置一个变量，你可以像这样打印出来：

v="my data"
echo "test" | awk 'BEGIN{var=ARGV[1];ARGV[1]=""} {print var, 
variable="line one\nline two"
awk 'BEGIN {print "'"$variable"'"}'
line one
line two
}' "$v"
my data test

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ARGVinput

ARGV输入

As Steven Penny writes, you can use ARGVto get the data into awk:

正如 Steven Penny 所写，您可以使用ARGV将数据导入 awk：

variable='line one\nline two" ; for (i=1;i<=1000;++i) print i"'
awk 'BEGIN {print "'"$variable"'"}'
line one
line two
1
2
3
.
.
1000

To get the data into the code itself, not just the BEGIN:

要将数据放入代码本身，而不仅仅是 BEGIN：

var="Line one
This is line two"

echo $var
Line one This is line two

echo "$var"
Line one
This is line two

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Variable within the code: USE WITH CAUTION

代码中的变量：谨慎使用

You can use a variable within the awkcode, but it's messy and hard to read, and as Charles Duffypoints out, this version may also be a victim of code injection. If someone adds bad stuff to the variable, it will be executed as part of the awkcode.

您可以在awk代码中使用变量，但它很混乱且难以阅读，而且正如Charles Duffy指出的那样，这个版本也可能是代码注入的受害者。如果有人向变量中添加了不好的东西，它将作为awk代码的一部分执行。

This works by extracting the variable within the code, so it becomes a part of it.

这是通过提取代码中的变量来工作的，因此它成为它的一部分。

If you want to make an awkthat changes dynamically with use of variables, you can do it this way, but DO NOT use it for normal variables.

如果您想awk使用变量动态更改，您可以这样做，但不要将它用于普通变量。

variable="line one\nline two"
awk -v var=$variable 'BEGIN {print var}'
awk: cmd. line:1: one\nline
awk: cmd. line:1:    ^ backslash not last character on line
awk: cmd. line:1: one\nline
awk: cmd. line:1:    ^ syntax error

Here is an example of code injection:

下面是一个代码注入的例子：

awk -v var='$variable' 'BEGIN {print var}'
$variable

You can add lots of commands to awkthis way. Even make it crash with non valid commands.

您可以通过awk这种方式添加大量命令。甚至使用无效命令使其崩溃。

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Extra info:

额外信息：

Use of double quote

双引号的使用

It's always good to double quote variable "$variable"
If not, multiple lines will be added as a long single line.

双引号变量总是好的"$variable"
如果不是，多行将作为一个长单行添加。

Example:

例子：

$ X=Solaris awk 'BEGIN{print ENVIRON["X"], ENVIRON["TERM"]}'
Solaris rxvt

Other errors you can get without double quote:

没有双引号可以得到的其他错误：

awk -v avar="$svar" '... avar ...' file
awk 'BEGIN{avar=ARGV[1];ARGV[1]=""}... avar ...' "$svar" file

And with single quote, it does not expand the value of the variable:

并且使用单引号，它不会扩展变量的值：

% awk -vv="${v}" 'BEGIN { print v }'
123test

More info about AWK and variables

有关 AWK 和变量的更多信息

Read this faq.

阅读此常见问题解答。

回答by TrueY

It seems that the good-old ENVIRONawkbuilt-in hash is not mentioned at all. An example of its usage:

似乎根本没有提到古老的ENVIRONawk内置哈希。其用法示例：

% environment_variable=123test
% awk -vawk_variable="${environment_variable}" 'BEGIN { print awk_variable }'
123test

回答by Ed Morton

Use either of these depending how you want backslashes in the shell variables handled (avaris an awk variable, svaris a shell variable):

根据您希望如何处理 shell 变量中的反斜杠（avar是一个 awk 变量，svar是一个 shell 变量），使用其中的任何一个：

v=123test
awk 'BEGIN {print ARGV[1]}' "$v"

See http://cfajohnson.com/shell/cus-faq-2.html#Q24for details and other options. The first method above is almost always your best option and has the most obvious semantics.

有关详细信息和其他选项，请参阅http://cfajohnson.com/shell/cus-faq-2.html#Q24。上面的第一种方法几乎总是您的最佳选择，并且具有最明显的语义。

回答by Johnsyweb

You could pass in the command-line option-vwith a variable name (v) and a value (=) of the environment variable ("${v}"):

您可以使用变量名 ( ) 和环境变量 ( )的值 ( )传入命令行选项：-vv="${v}"

awk 'BEGIN {ARGC--} {print ARGV[2], 
for i in `seq 11 20`; do host myserver-$i | awk -v i="$i" '{print "myserver-"i" " }'; done
}' file "$v"

Or to make it clearer (with far fewer vs):

或者让它更清楚（用更少的vs）：

DATE=$(date +"%Y-%m-%d")
awk '{ print "'"$DATE"'", ##代码##; }' /path_to_log_file/log_file.log

回答by Steven Penny

You can utilize ARGV:

您可以使用 ARGV：

##代码##

Note that if you are going to continue into the body, you will need to adjust ARGC:

请注意，如果您要继续进入正文，则需要调整 ARGC：

##代码##

回答by edib

I just changed @Jotne's answer for "for loop".

我刚刚更改了@Jotne 对“for 循环”的回答。

##代码##

回答by Sina

I had to insert date at the beginning of the lines of a log file and it's done like below:

我必须在日志文件行的开头插入日期，它的完成方式如下：

##代码##

It can be redirect to another file to save

它可以重定向到另一个文件进行保存