Remove blanks, convert hypens and underscores and fix extensions in file/directory names

fnmod.sh

#!/usr/bin/env bash

# Remove blanks
remove_blanks()
{
	[[ $N == *[' ']* ]] || return
	mv_to "$P/${N// /}"
}

# Convert hypens to underscores
convert_hyphens()
{
	[[ $F == *['-']* ]] || return
	mv_to "$P/${N//-/_}"
}

# Convert underscores to hypens
convert_underscores()
{
	[[ $F == *['_']* ]] || return
	mv_to "$P/${N//_/-}"
}

# Make extensions all lower case and fix annoying alternatives
fix_extensions()
{
	[[ $N == *.* ]] || return

	local E=${N##*.}
	local O=$E

	# convert upper to lower case
	[[ $E == *[ABCDEFGHIJKLMNOPQRSTUVWXYZ]* ]] && E=${E,,}

	# fix annoying extensions
	case "$E" in
		jpeg)
			E=jpg
			;;
	esac

	[ "$E" == "$O" ] && return
	mv_to "$P/${N%.*}.$E"
}

# Convert to lower case
lower_case()
{
	[[ $N == *[ABCDEFGHIJKLMNOPQRSTUVWXYZ]* ]] || return $?
	mv_to "$P/${N,,}"
}

# Rename $F to given name
#
# @param 1 - full path with new file name
mv_to()
{
	[ "$F" == "$1" ] && return
	mv -i "$F" "$1"
	F=$1
	strip_filename
}

# Strip path and name
strip_filename()
{
	P=${F%/*}
	N=${F##*/}
}

# Process directories recursively
#
# @param ... - flags and paths
process()
{
	local ARG ACTIONS='' DEPTH='-maxdepth 1' DIRS=''

	# if the last argument isn't a path, add CWD
	for ARG; do true; done
	[ -d "$ARG" ] || set -- "$@" '.'

	for ARG
	do
		if [[ $ARG == -* ]]
		then
			while read -r -n 1
			do
				[ "$REPLY" ] || continue
				case "$REPLY" in
					r)
						DEPTH=
						;;
					d)
						DIRS=d
						;;
					b)
						ACTIONS=$ACTIONS${ACTIONS:+ }remove_blanks
						;;
					t)
						ACTIONS=$ACTIONS${ACTIONS:+ }convert_hyphens
						;;
					u)
						ACTIONS=$ACTIONS${ACTIONS:+ }convert_underscores
						;;
					e)
						ACTIONS=$ACTIONS${ACTIONS:+ }fix_extensions
						;;
					l)
						ACTIONS=$ACTIONS${ACTIONS:+ }lower_case
						;;
					*)
						echo "error: unknown flag: $REPLY" >&2
						return 1
						;;
				esac
			done <<< "${ARG##*-}"
			continue
		elif ! [ -d "$ARG" ]
		then
			echo "error: $ARG is not a directory, skipping" >&2
			continue
		fi

		[ "$ACTIONS" ] || {
			echo 'error: you need to choose at least one action' >&2
			return 1
		}

		local T F P N A
		for T in $DIRS f
		do
			find "$ARG" "$DEPTH" -type "$T" | while read -r F
			do
				strip_filename

				for A in $ACTIONS
				do
					"$A" "$F"
				done
			done
		done
	done
}

[ "$1" ] || {
	cat <<EOF
usage: ${0##*/} [-rbhuel] [PATH]...
    -r    find files recursively
    -d    modify directory names also
    -b    remove blanks
    -t    convert hyphens to underscores
    -u    convert underscores to hyphens
    -e    fix extensions
    -l    make file name all lower case
EOF

	exit
}

if [ "${BASH_SOURCE[0]}" == "$0" ]
then
	process "$@"
fi