How to rename android assets recursively and replace dash for underscore

Question

I have some assets that my designer have created, he branched them correctly making all dpi's match their directories so I was happy because I didn't had to copy those files to each subfolder but when I checked out their names they had dashes in the filenames, which made android compiler to fail.

So how I can make a bash script to rename all files below drawable-*, to the same file name but replacing dashes with underscores?

Example:

Convert this :

drawable-hdpi/
    my-icon.png
    my-icon-2.png
drawable-xhdpi/
    my-icon.png
    my-icon-2.png
drawable-xxhdpi/
    my-icon.png
    my-icon-2.png

To this:

drawable-hdpi/
    my_icon.png
    my_icon_2.png
drawable-xhdpi/
    my_icon.png
    my_icon_2.png
drawable-xxhdpi/
    my_icon.png
    my_icon_2.png

Answer 1

Check out Bash FAQ 30 which discusses this subject in detail, along with provided examples.

Regarding your solution:

• Please note that by convention, environment variables (PATH, EDITOR, SHELL, ...) and internal shell variables (BASH_VERSION, RANDOM, ...) are fully capitalized. All other variable names should be lowercase. Since variable names are case-sensitive, this convention avoids accidentally overriding environmental and internal variables.

• "Double quote" every literal that contains spaces/metacharacters and every expansion: "$var", "$(command "$var")", "${array[@]}", "a & b". See Quotes, Arguments and http://wiki.bash-hackers.org/syntax/words.

TL;DR

find /paths/to/drawable/dirs -type f -name '*-*' -print0 \
| while read -rd '' f; do
    # File's path.
    p="${f%/*}"
    # File's base-name.
    f1="${f##*/}"
    # Lower-cased base-name.
    f1="${f1,,}"
    # Rename.
    echo mv "$f" "$p/${f1//-/_}"
  done

NOTE: The echo command is there on purpose, so that you won't accidently damage your files. Remove it when you're sure it is going to do what it is supposed to.

Answer 2

Not really a bash solution, but you can use the rename utility from Larry Wall:

rename -n 's#(?>\G(?!^)|.*/)[^-]*\K-#_#g' ./pathto/drawable-*/*

-n is to perform a test, when you are sure remove it.