经常会有这种情景：我们需要合并两个目录。
实际情况：mv命令不支持目录合并
看一个示例。当前目录下有两个目录a0与b0，同时b0中还有一个a0，但是这个两个a0目录的内容不同，我想合并这两个a0目录。目录结构如下：
# tree a0 b0
a0
└── a1
a0
└── a1
├── a1.txt
└── a2
└── a2
b0
├── a0
│ └── a1
│ └── a2
│ └── a2.txt
└── b1
├── a0
│ └── a1
│ └── a2
│ └── a2.txt
└── b1
└── b2
7 directories, 2 files
在我尝试将a0合并到b0/a0中时，mv命令返回了一个错误：
# mv a0 b0/
mv: cannot move ‘a0’ to ‘b0/a0’: Directory not empty
mv: cannot move ‘a0’ to ‘b0/a0’: Directory not empty
之所以返回这个错误是因为mv命令不支持目录合并。
实现目录合并的方法
不跨文件系统的解决方案
You can use the -l option of the cp command, which creates hard links of files on the same filesystem instead of full-data copies. The following command copies the folder source/folder to a parent folder (destination) which already contains a directory with the name folder.
cp -rl source/folder destination
rm -r source/folder
rm -r source/folder
Notes:
- You may also want to use the -P (–no-dereference – do not de-reference symbolic links) or -a (–archive – preserve all metadata, also includes -P option), depending on your needs.
- Though there are two “I/O” steps involved, the steps are relatively simple metadata operations involving zero “data” transfers. Thus this method is magnitudes faster than a cp (sans -l) or rsync-based solution.
- This does not work if your source and destination folders are on different filesystems
其他解决方案
BASH – merge directories when using mv
Merging folders with mv?
参考文献
BASH – merge directories when using mv
Merging folders with mv?