copy many files (same name) contained in different father folder

Question

I have a question about unix command line. I have many files like these:

/f/f1/file.txt

/f/f2/file.txt

/f/f3/file.txt

and so on.

I had like copy all file.txt with their father folder in another folder g like:

/g/f1/file.txt

/g/f2/file.txt

/g/f3/file.txt

I can't copy all content of folder f because in each sub-folder f1, f2, ... I have many other files that I don't want copy.

How could I do this with the command line? Eventually using a bash script?

Answer 1

Manual for cp shows this option -

--parents
              use full source file name under DIRECTORY

So if you are on bash v4 you can do something like this -

[jaypal:~/Temp/f] tree
.
├── f1
│   ├── file.txt  # copy this file only with parent directory f1
│   ├── file1.txt
│   └── file2.txt
└── f2
    ├── file.txt  # copy this file only with parent directory f2
    ├── file1.txt
    └── file2.txt

2 directories, 6 files
[jaypal:~/Temp/f] mkdir ../g
[jaypal:~/Temp/f] shopt -s globstar
[jaypal:~/Temp/f] for file in ./**/file.txt; do cp --parents "$file" ../g ; done
[jaypal:~/Temp/f] tree ../g
../g
├── f1
│   └── file.txt
└── f2
    └── file.txt

2 directories, 2 files

Answer 2

tar is sometimes helpful for coping files: see the small test:

kent$  tree t g
t
|-- t1
|   |-- file
|   `-- foo ---->####this file we won't copy
|-- t2
|   `-- file
`-- t3
    `-- file
g

3 directories, 4 files

kent$  cd t

kent$  find -name "file"|xargs tar -cf - | tar -xf - -C ../g

kent$  tree ../t ../g
../t
|-- t1
|   |-- file
|   `-- foo
|-- t2
|   `-- file
`-- t3
    `-- file
../g
|-- t1
|   `-- file
|-- t2
|   `-- file
`-- t3
    `-- file