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How to copy files preserving one directory up

+5
−0

Have

mkdir -p d1/d1_sd1/ d2/d2_sd1/
touch d1/d1_sd1/f1.txt d2/d2_sd1/f1.txt
.
├── d1
│   └── d1_sd1
│       └── f1.txt
└── d2
    └── d2_sd1
        └── f1.txt

4 directories, 2 files

Want

.
├── d1
│   └── d1_sd1
│       └── f1.txt
├── d1_sd1
│   └── f1.txt
├── d2
│   └── d2_sd1
│       └── f1.txt
└── d2_sd1
    └── f1.txt

6 directories, 4 files

Question

How do I cp files with a pattern preserving one directory up from the match?

I'd expect a modification to this call:

cp -r d*/*/f1.txt .

Tried

cp -r --parents d*/*/f1.txt .
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2 comment threads

cp only? Which cp? (5 comments)
./a/b/c/d ---> ./c/d ? (2 comments)

1 answer

+4
−0

Assuming innermost directories are not empty, in any POSIX compliant system,

find . -type d -links 2 -exec cp -r {} . \;

In a GNU Linux system, a more performant alternative is

find . -type d -links 2 -exec cp -rt . {} +

since it only spawns an optimal number of cp process (a single one if the size of the argument list is not large).

How does it work?

Leaf directories have only two hard links

Every directory in a Linux system is indexed with at least two hard links.

A leaf directory, by definition a directory without any sub-directory, has only two hard links, path/to/dir and path/to/dir/..

On the other hand, a directory with one sub-directory would have an additional hard link, namely path/to/dir/subdir/...

Conclusion: The number h of hard links of a directory is h=s+2, being s the number of sub-directories.

The -exec option

The -exec option executes the corresponding command for each found file if ; terminated or for the maximum number of files if + terminated. So, for example, the first will spawn

cp -r d1_sd1 .
cp -r d3_sd2 .

while the latter will spawn

cp -rt . d1_sd1 d3_sd2

See that the latter is only possible because the -t option, available in cp from GNU coreutils, allows the target to be specified before the files to be copied. (-exec cp -r {} . + is not valid!)

Before

$ tree
./
├── d1/
│   └── d1_sd1/
│       └── f1.txt
└── d3/
    └── d3_sd1/
        └── d3_sd2/
            └── f1.txt

5 directories, 2 files

After

$ tree
./
├── d1/
│   └── d1_sd1/
│       └── f1.txt
├── d1_sd1/
│   └── f1.txt
├── d3/
│   └── d3_sd1/
│       └── d3_sd2/
│           └── f1.txt
└── d3_sd2/
    └── f1.txt

7 directories, 4 files
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1 comment thread

Trouble understanding your leaf discussion. (3 comments)

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