使用awk从文件创建单词索引

This is an example file.
It contains some words for demonstration purposes.
The words may appear multiple times.

awk '{
    for (i=1; i<=NF; i++) {
        word = tolower($i);  # 将单词转换为小写
        if (word in words) {
            words[word]++;  # 单词已存在，增加出现次数
        } else {
            words[word] = 1;  # 单词不存在，初始化出现次数为1
        }
        if (!(word in positions)) {
            positions[word] = NR;  # 记录单词第一次出现的行号
        }
    }
}
END {
    for (word in words) {
        print "单词: " word;
        print "出现次数: " words[word];
        print "第一次出现的行号: " positions[word];
        print "------------------------";
    }
}' example.txt