如何使用 sed/awk 替换逗号分隔字符串中的第 n 列/字段? [英] How to replace the nth column/field in a comma-separated string using sed/awk?

问题描述

假设我有一个字符串

"1,2,3,4"

现在我想替换，例如字符串的第三个字段由一些不同的值.

Now I want to replace, e.g. the 3rd field of the string by some different value.

"1,2,NEW,4"

我使用以下命令设法做到了这一点:

I managed to do this with the following command:

echo "1,2,3,4" | awk -F, -v OFS=, '{$3="NEW"; print }'

现在要替换的列的索引应该作为变量传递.所以在这种情况下

Now the index for the column to be replaced should be passed as a variable. So in this case

index=3

如何将其传递给 awk?因为这行不通:

How can I pass this to awk? Because this won't work:

echo "1,2,3,4" | awk -F, -v OFS=, '{$index="NEW"; print }'
echo "1,2,3,4" | awk -F, -v OFS=, '{$($index)="NEW"; print }'
echo "1,2,3,4" | awk -F, -v OFS=, '{$$index="NEW"; print }'

感谢您的帮助！

推荐答案

在awk程序中让shell插入索引:

Have the shell interpolate the index in the awk program:

echo "1,2,3,4" | awk -F, -v OFS=, '{$'$index'="NEW"; print }'

注意最初的单引号 awk 程序是如何分成三个部分的，一个单引号开头的 '{$'，插入的索引值，然后是程序的单引号剩余部分.

Note how the originally single quoted awk program is split in three parts, a single quoted beginning '{$', the interpolated index value, followed by the single quoted remainder of the program.

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