您可能可以使用文件系统本身作为哈希表。伪代码如下:

for every entry in the ip address file; do
  let addr denote the ip address;

  if file "addr" does not exist; then
    create file "addr";
    write a number "0" in the file;
  else 
    read the number from "addr";
    increase the number by 1 and write it back;
  fi
done

最后，您所需要做的就是遍历所有文件，并在其中打印文件名和编号。或者，您可以每次在文件中附加一个空格或换行符，而不是保持计数，最后只需查看文件大小(以字节为单位)。

又快又脏的方法如下:

Cat ip_addresses | sort -n | uniq -c

如果需要使用bash中的值，可以将整个命令赋值给一个bash变量，然后循环遍历结果。

PS

如果省略sort命令，就不会得到正确的结果，因为uniq只查看连续的相同行。

典型的解决方案是另一位受访者提到的:

sort | uniq -c

它比用Perl或awk编写的代码更短、更简洁。

You write that you don't want to use sort, because the data's size is larger than the machine's main memory size. Don't underestimate the implementation quality of the Unix sort command. Sort was used to handle very large volumes of data (think the original AT&T's billing data) on machines with 128k (that's 131,072 bytes) of memory (PDP-11). When sort encounters more data than a preset limit (often tuned close to the size of the machine's main memory) it sorts the data it has read in main memory and writes it into a temporary file. It then repeats the action with the next chunks of data. Finally, it performs a merge sort on those intermediate files. This allows sort to work on data many times larger than the machine's main memory.

大多数其他解决方案计算重复。如果你真的需要分组键值对，试试这个:

以下是我的示例数据:

find . | xargs md5sum
fe4ab8e15432161f452e345ff30c68b0 a.txt
30c68b02161e15435ff52e34f4fe4ab8 b.txt
30c68b02161e15435ff52e34f4fe4ab8 c.txt
fe4ab8e15432161f452e345ff30c68b0 d.txt
fe4ab8e15432161f452e345ff30c68b0 e.txt

这将打印按md5校验和分组的键值对。

cat table.txt | awk '{print $1}' | sort | uniq  | xargs -i grep {} table.txt
30c68b02161e15435ff52e34f4fe4ab8 b.txt
30c68b02161e15435ff52e34f4fe4ab8 c.txt
fe4ab8e15432161f452e345ff30c68b0 a.txt
fe4ab8e15432161f452e345ff30c68b0 d.txt
fe4ab8e15432161f452e345ff30c68b0 e.txt

cat ip_addresses | sort | uniq -c | sort -nr | awk '{print $2 " " $1}'

这个命令将提供您想要的输出

sort ip_addresses | uniq -c

这将首先打印计数，但除此之外，它应该完全是您想要的。