将变量传递给awk并在正则表达式中使用它 [英] Passing variable to awk and using that in a regular expression
问题描述
我正在学习awk，在将变量传递到脚本并将其用作正则表达式搜索模式的一部分时遇到了麻烦.
I'm learning awk and I have trouble passing a variable to the script AND using it as part of a regex search pattern.
该示例是人为设计的，但显示了我的探针.
The example is contrived but shows my probem.
我的数据如下:
Eddy Smith 0600000000 1981-07-16 Los Angeles
Frank Smith 0611111111 1947-04-29 Chicago
Victoria McSmith 0687654321 1982-12-16 Los Angeles
Barbara Smithy 0633244321 1984-06-24 Boston
Jane McSmithy 0612345678 1947-01-15 Chicago
Grace Jones 0622222222 1985-10-07 Los Angeles
Bernard Jones 0647658763 1988-01-01 New York
George Jonesy 0623428948 1983-01-01 New York
Indiana McJones 0698732298 1952-01-01 Miami
Philip McJonesy 0644238523 1954-01-01 Miami
我想要一个可以传递变量的awk脚本，然后让awk脚本对该变量进行正则表达式. 我现在有了这个脚本，名称为"003_search_persons.awk".
I want an awk script that I can pass a variable and then have the awk script do a regex for the variable. I've got this script now called "003_search_persons.awk".
#this awk script looks for a certain name, returns firstName, lastName and City
#print column headers
BEGIN {
printf "firstName lastName City\n";
}
#look for the name, print firstName, lastName and City
$2 ~ name {
printf $1 " " $2 " " $5 " " $6;
printf "\n";
}
我这样称呼脚本:
awk -f 003_search_persons.awk name=Smith 003_persons.txt
它返回以下内容，这很好.
It returns the following, which is good.
firstName lastName City
Eddy Smith Los Angeles
Frank Smith Chicago
Victoria McSmith Los Angeles
Barbara Smithy Boston
Jane McSmithy Chicago
但是现在我要查找某个前缀"Mc".我当然可以对此进行硬编码，但是我想要一个灵活的awk脚本.我在003_search_persons_prefix.awk中写了以下内容.
But now I want to look for a certain prefix "Mc". I could ofcourse hardcode this, but I want an awk script that is flexible. I wrote the following in 003_search_persons_prefix.awk.
#this awk script looks for a certain prefix to a name, returns firstName, lastName and City
#print column headers
BEGIN {
printf "firstName lastName City\n";
}
#look for the prefix, print firstName, lastName and City
/^prefix/{
printf $1 " " $2 " " $5 " " $6;
printf "\n";
}
我这样称呼脚本:
awk -f 003_search_persons_prefix.awk prefix=Mc 003_persons.txt
但是现在找不到任何记录.
But now it finds no records.
问题是搜索模式"/^ prefix/".我知道我可以像第一个脚本中那样用非正则表达式替换该搜索模式，但是假设我想用正则表达式进行搜索，因为我需要前缀确实位于lastName字段的开头，因为它应该是前缀和所有;-)
The problem is the search pattern "/^prefix/". I know I can replace that search pattern by a non-regex one, as in the first script, but suppose I want to do it with a regex, because I need the prefix to really be at the start of the lastName field, as it should be, being a prefix and all ;-)
我该怎么做?
推荐答案
您可以尝试
BEGIN{
printf "firstName lastName City\n";
split(ARGV[1], n,"=")
prefix=n[2]
pat="^"prefix
}
$0 ~ pat{
print "found: "$0
}
输出
$ awk -f test.awk name=Jane file
firstName lastName City
found: Jane McSmithy 0612345678 1947-01-15 Chicago
有关更多信息，请参见 awk文档. (并从头到尾阅读它！)
Look at the awk documentation for more. (and read it from start to finish!)
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