Awk脚本处理CSV合并数组列时额外输出原始行问题求助

问题原因 #

你的awk脚本末尾存在多余的独立关键字FILENAME。
awk的语法规则为「匹配模式 { 执行动作 }」，如果只写了匹配模式没有指定对应的动作，默认会执行打印当前行的操作。因此每一行完成你编写的格式转换逻辑后，都会再触发一次默认打印逻辑，输出原始未处理的行，最终出现重复内容。

修复方案 #

直接删除脚本末尾孤零零的FILENAME字符串即可，修改后的完整脚本如下：

#!/bin/awk -f

BEGIN {
        getline;
        print $0;
        num_cols = NF;

        #printf("num_cols: %s, array_col: %s\n\n", num_cols, array_col);
}
NR>1 {
        total_fields = NF;

        # fields_before_array = (array_col - 1)
        # fields_before_array + array_length + fields_after_array = NF
        # fields_before_array + fields_after_array + 1 = num_cols
        # array_length - 1 = total_fields - num_cols
        # array_length = total_fields - num_cols + 1
        # fields_after_array = total_fields - array_length - fields_before_array
        #                    = total_fields - (total_fields - num_cols + 1) - (array_col - 1)
        #                    = num_cols - array_col
        fields_before_array = (array_col - 1);
        array_length = total_fields - num_cols + 1;
        fields_after_array = num_cols - array_col;
        first_array_position = array_col;
        last_array_position = array_col + array_length-1;

        #printf("array_col: %s, fields_before_array: %s, array_length: %s, fields_after_array: %s, total_fields: %s, num_cols: %s", array_col, fields_before_array, array_length, fields_after_array, total_fields, num_cols)

        ### loop through fields before array column
        ### remove whitespace, and print surround with ""
        for (i=1; i<array_col; i++)
        {
          gsub(/ /,"",$i);
          printf("\"%s\",", $i);
        }

        ### Collect array surrounded by ""
        array_data = "";

        ### Loop through array
        for (i=array_col ; i<array_col+array_length-1 ; i++)
        {
          gsub(/ /, "", $i);
          array_data = array_data $i ",";
        }

        ### collect last array element with no trailing ,
        array_data = array_data $i

        ### print array surrounded by quotes
        printf("\"%s\",", array_data);

        ### loop through remaining fields, remove whitespace, surround with ""
        for (i=last_array_position+1 ; i<total_fields ; i++)
        {
          gsub(/ /,"",$i);
          printf("\"%s\",", $i);
        }

        ### finish line with \n
        printf("\"%s\"\n", $total_fields);
}

修改后重新运行脚本即可得到你预期的输出结果。

内容的提问来源于stack exchange，提问作者abalter