find ./directory -name \*.mp3 -exec cp {} distination_directory \;

#!/bin/bash

# fcopy.sh
#
# selectively copies files
#
# usage: [bash|.] fcopy.sh <source directory> <target directory> <ext1, [ext2, ...]>
#

LOG_VERBOSE=false

function log_message {
	echo "fcopy: $1"
}

function log_error {
	message "error: $1" >&2
}

function log_warning {
	message "warning: $1"
}

function log_verbose {
	if [[ $LOG_VERBOSE = true ]]; then
		function log_verbose { echo "fcopy: $1"; }
	else
		function log_verbose { :; }
	fi
	log_verbose "$1"  # doing this might not be safe but it is
}

function show_usage {
	message "usage: $0 -h|--help|-? | [-v|--verbose] <source directory> <target directory> <ext1, [ext2, ...]>"
}

function fail {
	log_error "$1"
	exit 1
}

function check_directory {
	[[ -d $1 ]] || fail "specified $2 $1 does not appear to be directory."
	[[ ! -r $1 || ! -x $1 ]] && fail "specified $2 $1 is not searcheable or changeable."
}

function getabspath {

	# loader-lite-0L.WP20100217.tar.gz @ sf.net/projects/loader

	local -a T1 T2=()
	local -i I=0
	local IFS=/ A

	if [[ $1 == /* ]]; then
		read -a T1 <<< "$1"
	else
		read -a T1 <<< "$PWD/$1"
	fi

	for A in "${T1[@]}"; do
		case "$A" in
		..)
			[[ I -ne 0 ]] && unset T2\[--I\]
			continue
			;;
		.|'\'\'')
			continue
			;;
		esac

		T2[I++]=$A
	done

	if [[ $1 == */ ]]; then
		if [[ I -ne 0 ]]; then
			__="/${T2[*]}/"
		else
			__=/
		fi
	else
		if [[ I -ne 0 ]]; then
			__="/${T2[*]}"
		else
			__=/.
		fi
	fi
}

function main {
	local SOURCEDIR='?' DESTDIR='?' CMD A __

	# parse / check arguments

	for (( ; $#; )); do
		case "$1" in
		-h|--help|-\?)
			show_usage
			exit 1
			;;
		-v|--verbose)
			LOG_VERBOSE=true
			;;
		*)
			if [[ $SOURCEDIR = '?' ]]; then
				SOURCEDIR=$1
			elif [[ $DESTDIR = '?' ]]; then
				DESTDIR=$1
			else
				break
			fi
			;;
		esac

		shift
	done

	if [[ $# -eq 0 ]]; then
		log_error "not enough arguments."
		show_usage
		exit 1
	fi

	# get the absolute paths

	getabspath "$SOURCEDIR/."; SOURCEDIR=$__
	getabspath "$DESTDIR/."; DESTDIR=$__

	# check the extensions

	for A; do
		if [[ $A != [[:alnum:]_] ]]; then  # change this if some characters are also required
			log_warning "extension $A may not be valid."
		fi
	done

	# check the directories, also create destination directory if needed

	check_directory "$SOURCEDIR" "source directory"

	pushd "$SOURCEDIR" || fail "failed to change current working directory to $SOURCEDIR"

	if [[ ! $DESTDIR = /. || -e $DESTDIR ]]; then
		check_directory "$DESTDIR" "destination directory"
	else
		mkdir -p "$DESTDIR" || fail "failed to create destination directory $DESTDIR."
	fi

	# prepare the command

	CMD="find -type f -name '*.$A'"
	shift

	for A; do
		CMD=$CMD" -or -name '*.$A'"
	done

	# copy

	while read -u 3 A; do
		log_verbose "copying $A..."
		cp --parent -v "$A" "$DESTDIR" && continue
		log_warning "failed to copy $A.  press any key to continue.."
		read -s -n 1 -p
	done 3< <(eval exec "$CMD")

	popd  # output pushd and popd may also be redirected to /dev/null

	exit 0
}

( main "$@"; )

#!/bin/bash

abort () { echo "ABORTED: $1 missing or doesn't exist!"; usage; }
usage () { echo -e "$0: [-s source dir] [-d dest dir] [-e extention,extention,extention,...]\nex: $0 -s $HOME -d /tmp -e jpg,png,mp3"; exit; }

if [ ! "$1" ]; then usage; fi
until [ -z "$1" ]; do
        case "$1" in
                "-s")   shift; SOURCEDIR="$1";;
                "-d")   shift; DESTDIR="$1";;
                "-e")   shift; EXTENTIONS=( `echo "$1" |sed 's/,/ /g'` );;
                *)      usage;;
        esac
        shift
done

if [ ! "$SOURCEDIR" ] || [ ! -e "$SOURCEDIR" ]; then abort "source dir"; fi
if [ ! "$DESTDIR" ] || [ ! -e "$DESTDIR" ]; then abort "destination dir"; fi
if [ "${#EXTENTIONS[@]}" == "0" ]; then abort "extention(s)"; fi

echo -e "using source     : $SOURCEDIR\nusing destination: $DESTDIR"

for ITEM in "${EXTENTIONS[@]}"; do
        if echo $CHECK |grep $ITEM &>/dev/null; then continue; fi
        CHECK="$CHECK $ITEM"
        while read file; do
                echo "copying $SOURCEDIR/$file to $DESTDIR/$file"
                if [ ! -e "$DESTDIR/`dirname $file`" ]; then mkdir "$DESTDIR/`dirname $file`"; fi
                cp "$SOURCEDIR/$file" "$DESTDIR/$file"
        done < <(find "$SOURCEDIR" -type f -name "*$ITEM" -printf "%P\n")

done

                *)      usage;;

cp --parents a/b.txt c

files/0.EXT1
files/a.EXT2
files/Z.EXT1
files/_.EXT2

files/0.EXT1
files/Z.EXT1
files/a.EXT2
files/_.EXT2