cp 在 Mac 上的工作方式不同

Question

我有以下代码来复制整个文件夹：

#!/bin/bash

B="H:\pdf2txt"

DST_DIR="H:\Test_Folder"

cp -r "$B" "$DST_DIR"

这在 Windows 机器上按预期工作，但是当我将它更改为我的 Mac 时：

#!/bin/bash

B="/Volumes/Mac_Storage/pdf2txt"

DST_DIR="/Volumes/Mac_Storage/Test_folder"

cp -r "$B" "$DST_DIR"

它复制文件夹，然后在该文件夹中添加另一个副本，内容相同，然后再次相同，直到文件路径太长，mac无法处理。文件夹结构如下：

Test_Folder
|   ??? pdf2txt 
|       ??? test1.txt
|       ??? test2.txt
|       ??? pdf2txt
|           ??? test1.txt
|           ??? test2.txt
|           ??? pdf2txt
|               ??? test1.txt
|               ??? test2.txt
|               ??? pdf2txt
|                   ??? test1.txt
|                   ??? test2.txt
|                   ??? pdf2txt
|                       ??? test1.txt
|                       ??? test2.txt
|                       ??? pdf2txt
|                           ??? test1.txt
|                           ??? test2.txt
|                           ??? pdf2txt

等等等等。

知道为什么它从 Windows 到 Mac 的工作方式不同吗？

Answer 1

我认为telcoM 的回答嗅到了主要原因：它可能涉及一个符号链接，只是一个不同的符号链接。

根据我的实验，有一组情况符合要求：

• Test_folder是到 的符号链接pdf2txt，并且
• OP 使用的是股票 macOS cp，它具有 BSD 传统

这种符号链接会破坏 macOScp的循环检测。（GNU cp，正如Homebrew或其他一些包管理器所安装的那样，默认情况下不遵循符号链接，即使在递归复制时也是如此。）

这是一个在 macOS High Sierra 上测试的演示：

$ ln -s pdf2txt Test_folder

$ ls -lAF Test_folder
lrwxr-xr-x 1 aho staff 7 Feb 13 20:13 Test_folder -> pdf2txt/

$ /bin/cp -r pdf2txt Test_folder
cp: Test_folder/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt: name too long (not copied)
cp: Test_folder/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt: name too long (not copied)

# Let's just look at the first 30 lines of a recursive ls
# (And yes, we're looking at pdf2txt)
$ ls -lRAF pdf2txt | head -n 30
pdf2txt:
total 0
drwxr-xr-x+ 5 aho staff 170 Feb 13 20:13 pdf2txt/
-rw-r--r--+ 1 aho staff   0 Feb 13 19:43 test1.txt
-rw-r--r--+ 1 aho staff   0 Feb 13 19:43 test2.txt

pdf2txt/pdf2txt:
total 0
drwxr-xr-x+ 3 aho staff 102 Feb 13 20:13 pdf2txt/
-rw-r--r--+ 1 aho staff   0 Feb 13 20:13 test1.txt
-rw-r--r--+ 1 aho staff   0 Feb 13 20:13 test2.txt

pdf2txt/pdf2txt/pdf2txt:
total 0
drwxr-xr-x+ 3 aho staff 102 Feb 13 20:13 pdf2txt/

pdf2txt/pdf2txt/pdf2txt/pdf2txt:
total 0
drwxr-xr-x+ 3 aho staff 102 Feb 13 20:13 pdf2txt/

pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt:
total 0
drwxr-xr-x+ 3 aho staff 102 Feb 13 20:13 pdf2txt/

pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt:
total 0
drwxr-xr-x+ 3 aho staff 102 Feb 13 20:13 pdf2txt/

pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt/pdf2txt:
total 0

Answer 2

是否有/Volumes/Mac_Storage/pdf2txt/pdf2txt指向的符号链接.？

跑去ls -l /Volumes/Mac_Storage/pdf2txt检查。

如果你看到这样的一行：

lrwxrwxrwx 1 madmiddle madmiddle 1 Feb 12 12:34 pdf2txt -> .

……这就是原因。

创建这样一个链接的命令是ln -s . pdf2txt，这可能很容易由于打字错误而意外发生。