How to put a file in the current working directory in all subfolders (and maybe their subfolders, depending on what you want to do)

This will put the file in all of the subfolders, but not their subfolders:

for d in */; do cp water.txt "$d"; done

This will put the file water.txt (change all instances of water.txt to the filename you want to copy) in all the subfolders and their subfolders

for i in ./* # iterate over all files in current dir

do

    if [ -d "$i" ] # if it's a directory

    then

        cp water.txt "$i" # copy water.txt into it

    fi

done

Info from this linuxquestions thread