How to create a file for every directory on a tree?

Question

For the following tree structure:

    .
└── dir1
    └── dir2
        └── dir3

What would be a simple way to create a file (could be empty), for every directory, so the resulting tree will look like:

.
├── dir1
│   ├── dir2
│   │   ├── dir3
│   │   │   └── README
│   │   └── README
│   └── README
└── README

Answer 1

With zsh:

touch -- README **/*(N/e[REPLY+=/README])

It combines recursive globbing (**/*) with glob qualifiers, which here are:

• Nullglob: doesn't trigger an error if there's no match.
• /: restrict to files of type directory
• e[code]: evaluates the code for each file, here appending /README to file path (stored in $REPLY in the evaluated code).

Or you could use an anonymous function which is passed the list of directories, and which appends the /README to each in the arguments it passes to touch:

() {touch -- $^@/README} . **/*(N/)

(with rc-style array expansion for the anonymous function @rguments using the $^array syntax).

In all those, you can add the Dotglob glob qualifier to also add README to hidden directories.

Answer 2

You can do that with find:

find . -mindepth 1 -type d -exec touch "{}/README" \;

Explanation

• -mindepth 1 will set the minimum depth, to avoid including the current directory
• -type d will only find directories
• -exec will run a command
• {} contains the path of the found directory

If you want to use only builtin shell commands:

for dir in *; do if [ -d "$dir" ]; then touch "$dir/README"; fi; done

Explanation

• for will loop over every element in *, meaning all files in the current directory. dir will contain the current element during the loop.
• if [ -d $dir ] checks if the element is a directory and only then
• creates a file called README in the directory name contained in $dir