Cygwin Uniq不起作用

Question

给定以下排序文件（myfile.txt）：

http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
http://quarterly.mayo.edu/photolisting/default.cfm?summary=&displaymode=&reporting_unit_code=

当我尝试时：

uniq -c myfile.txt

我得到：

21 http://quarterly.mayo.edu/photoListing/default.cfm?summary=&displaymode=&reporting_unit_code=
   1 http://quarterly.mayo.edu/photolisting/default.cfm?summary=&displaymode=&reporting_unit_code=

我想这可能表明隐藏的角色或其他东西 - 但是当我尝试时：

uniq -u myfile.txt

我得到了预期：

http://quarterly.mayo.edu/photolisting/default.cfm?summary=&displaymode=&reporting_unit_code=

这是真正的不一致，还是我错过了什么？谢谢铝

Answer 1

uniq -u只打印唯一的行。您的myfile.txt显然有 21 条相同的行，后跟一条独特的行。 uniq -u只打印那一行唯一的行。

uniq myfile.txt应打印两行，第一行对应于 21 行相同的行，第二行对应于最后的不匹配行。

例如：

$ ( echo foo ; echo foo ; echo bar ) | uniq -c
      2 foo
      1 bar
$ ( echo foo ; echo foo ; echo bar ) | uniq -u
bar
$

至于为什么uniq -c产生 2 行输出而不是 1 行，那是因为你的最后一行与前面的 21 行不同。第 1..21 行有 photoListing（大写 L），第 22 行有 photolisting（小写 l）。

（我的第一个想法是，文件中可能有一些隐藏字符;因为你在Cygwin上，不一致的行尾是最有可能的罪魁祸首。要查看隐藏字符，请执行以下操作：

uniq -c myfile.txt | cat -A

但事实证明这不是问题所在。