bash awk 的 $1 与 shell 脚本中的 $1 冲突
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awk's $1 conflicts with $1 in shell script
提问by James Bond
I am writting a shell script which includes a couple of awk lines
我正在编写一个包含几行 awk 的 shell 脚本
the awk line looks like:
awk 行看起来像：
cat input.csv | awk -F, '~// {print "is good"}'
the first $1is the first column of the input csv, the second $1is supposed to be the first command line input of this shell script
第一个$1是输入csv的第一列，第二个$1应该是这个shell脚本的第一个命令行输入
I tried to put a \in front of the second $, but it seems to be not working.
我试图将 a\放在第二个前面$，但似乎不起作用。
Can anyone help?
任何人都可以帮忙吗？
回答by Adrian Pronk
cat input.csv | awk -F, '~/'""'/ {print "is good"}'
You need to close the 'string, insert the shell $1(inside "in case there are special characters), then reopen the 'string.
您需要关闭'字符串，插入外壳$1（内部"以防有特殊字符），然后重新打开'字符串。
And you may want to check whether the $1from shell contains /characters which will
upset the regular expression.
并且您可能想要检查$1from shell是否包含/会扰乱正则表达式的字符。
And as @Ignacio Vazquez-Abrams indicated, you don't need to pipe the output of catto awk, you can just get awkto read the file directly. That is:
正如@Ignacio Vazquez-Abrams 所指出的，您不需要将 的输出通过管道cat传输到 awk，您只需awk直接读取文件即可。那是：
cat input.csv | awk ...
can be simplified to:
可以简化为：
awk ... < input.csv
回答by Ignacio Vazquez-Abrams
A variable is fine too.
一个变量也很好。
awk -F, -v needle="" ' ~ needle {print "is good"}' < input.csv
回答by jlliagre
cat or a redirection isn't needed. Here is a third variant using backslash:
cat 或不需要重定向。这是使用反斜杠的第三种变体：
awk -F, "$1~// {print \"is good\"}" input.csv
