Move files with same name from sub-directories

mv-from-sub-dirs.sh

#! /bin/bash

# mv e.g. /dir/00[1|2|3]/file.ext -> /dir/file-[1...3].ext

idx=1         # start index for new file-names (use 0 or zero-based index)
ext=".ext"    # file extension (can be a wildcard)
from="/dir/*" # where to look for files
to="."        # target of mv command, e.g. "dir/"

for file in $from/*$ext; do
    mv "$file" `printf $to/$(basename $file $ext)-%03d$ext $idx`
    idx=$((idx+1))
done

# one-liner
# for file in $from/*$ext; do mv "$file" `printf $to/$(basename $file $ext)-%03d$ext $idx` && idx=$((idx+1)); done

# clear variables
unset idx ext from to