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LanceBaynes
Asked: 2011-01-18 01:03:56 +0800 CST

Using "touch" to create directories - create "shadow" copy of directories recursively

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  1. In the "A" directory: find . -type f > a.txt
  2. In the "B" directory: cat a.txt | while read FILENAMES; do touch "$FILENAMES"; done

Result: Step 2 "creates the files" (I mean only with the same filename, but with 0 Byte size) but if there are subdirs in the "A" directory, then step 2 can't create the files in the subdir, because there are no directories in it.

Question: Is there a way, that "touch" can create directories?

linux bash

5 Answers

  1. quick shot:

    while read FILENAME
do
  mkdir -p $(dirname "$FILENAME") && touch "$FILENAME"
done < a.txt

    Be aware of special chars (whitespaces, ...) in file-/pathnames and so on ...

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  2. I'm on quite a GNU parallel kick lately. Here's a way to do this in one line using that tool: 

    find A -type d | parallel 'mkdir -p B/$(dirname {})' && find . -type f | parallel 'touch B/{}'

    Note that this is inefficient because it runs a lot of extra unneeded mkdir -p for intermediary directories. That should be optimized if you are dealing with really huge directory structures.

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  3. Best Answer

    in the original, "A" directory:

    find . -type f > a.txt

    "B" directory:

    while read file; do if [[ "$file" = */* ]]; then mkdir -p "${file%/*}"; fi; touch "$file"; done < a.txt
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  4. This works even if A contains the file:

    A/My brother's 12" records dir/My brother's 12" records

    (cd A; find . -type f) | (cd B; parallel 'mkdir -p {//}; touch {}')

    Having dealt with users creating "creative" filenames I always test script like these on 

    My brother's 12" records

    If it works for that, then chances are good it will not fail.

    Thanks to Phil H for giving the basic building blocks.

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  5. Before doing:

    cat a.txt | while read FILENAMES; do touch "$FILENAMES"; done

    do:

    cat a.txt | sed -e `s|/[^/]*$||` | uniq | while read DIRNAMES; do mkdir -p "$DIRNAMES"; done

    As already pointed out, be careful about special char in dirnames/filenames, especially slashes (I would hate to have a file named "aaa/ccc", but it is always possible).

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