A lot of fixes (see description)

- fix indentation (I used a broken vim config)
- add a -d (dry run) option
- add guarding double quotes at a few places
- use `python3` if no `python` executable exists
- explicitly use bash (instead of posix sh) where it is required

init.sh

@@ -1,6 +1,19 @@
 #!/usr/bin/env sh
+
+CUSTOM_PYTHON=
+
+if ! which python > /dev/null; then
+	if which python3 > /dev/null; then
+		echo ">>> python not found, using python3 instead"
+		CUSTOM_PYTHON=python3
+	else
+		echo ">>> No python executable found, please install python or python3"
+		exit 1
+	fi
+fi
+
 if [ -e yt-dlc/ ]; then
-    echo ">>> youtube-dlc already downloaded, delete and redownload? [y/N]"
+	printf ">>> youtube-dlc already downloaded, delete and redownload? [y/N]: "
 	read RES
 	[ "$RES" = "y" ] || [ "$RES" = "Y" ] && rm -rf yt-dlc/
 fi
@@ -13,3 +26,5 @@ if [ ! -e yt-dlc/ ]; then
 fi
 echo ">>> Building youtube-dlc"
 make -C yt-dlc/ youtube-dlc
+[ -n "$CUSTOM_PYTHON" ] &&
+	sed -i "1c\\#!/usr/bin/env $CUSTOM_PYTHON" yt-dlc/youtube-dlc

southpark-downloader.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env sh
+#!/usr/bin/env bash
 
 source "$(dirname "$0")/config.sh"
 
@@ -34,14 +34,15 @@ usage() {
 	echo " -D                                        -  Download episodes in German"
 	echo " -u                                        -  Update episode index (default)"
 	echo " -U                                        -  Skip episode index update"
+	echo " -d                                        -  Dry run: don't download, just print out URLs"
 }
 
-unset OPT_SEASON OPT_EPISODE OPT_ALL OPT_EN OPT_LANG OPT_PROGRESS OPT_UPDATE_INDEX
+unset OPT_SEASON OPT_EPISODE OPT_ALL OPT_EN OPT_LANG OPT_PROGRESS OPT_UPDATE_INDEX OPT_DRY
 OPT_LANG="EN"
 OPT_PROGRESS=true
 OPT_UPDATE_INDEX=true
 
-while getopts "pPEDuUas:e:h" arg; do
+while getopts "pPEDuUdas:e:h" arg; do
 	case "$arg" in
 		h)
 			usage
@@ -75,6 +76,9 @@ while getopts "pPEDuUas:e:h" arg; do
 		U)
 			unset OPT_UPDATE_INDEX
 			;;
+		d)
+			OPT_DRY=true
+			;;
 		?)
 			usage
 			exit 1
@@ -96,14 +100,14 @@ update_index() {
 	[ ! -e "$INDEX_FILENAME" ] && echo "$INDEX_INITIAL_URL" > "$INDEX_FILENAME"
 	echo -ne "\e[32m>>> Updating episode index\e[m"
 	while true; do
-	local URL=$(tail -n1 "$INDEX_FILENAME")
+		local URL="$(tail -n1 "$INDEX_FILENAME")"
-	local NEWURLS=$(curl -s "$URL" | grep -o "$REGEX_EPISODE_URL" | tr -d "\"" | sed -E "s/^/https:\/\/www.southpark.de/g")
+		local NEWURLS="$(curl -s "$URL" | grep -o "$REGEX_EPISODE_URL" | tr -d "\"" | sed -E "s/^/https:\/\/www.southpark.de/g")"
-	[ "$URL" = $(printf "$NEWURLS" | tail -n1) ] && break
+		[ "$URL" = "$(printf "$NEWURLS" | tail -n1)" ] && break
 		echo "$NEWURLS" >> "$INDEX_FILENAME"
 		echo -ne "\e[32m.\e[m"
 	done
 	# The awk command removes duplicate lines
-    local NEW_INDEX=$(awk '!x[$0]++' "$INDEX_FILENAME")
+	local NEW_INDEX="$(awk '!x[$0]++' "$INDEX_FILENAME")"
 	printf "$NEW_INDEX" > "$INDEX_FILENAME"
 	echo
 }
@@ -142,7 +146,7 @@ monitor_progress() {
 	local TMP_DIR="$1"
 	while true; do
 		[ ! -e "$TMP_DIR" ] && break
-	printf " Downloaded: %s\r" $(du -bB M "$TMP_DIR" | cut -f1)
+		printf " Downloaded: %s\r" "$(du -bB M "$TMP_DIR" | cut -f1)"
 		sleep 0.5
 	done
 }
@@ -167,11 +171,12 @@ download_episode() {
 	local EPISODE_NUMBER="$2"
 	local OUTFILE="${OUTDIR}/South_Park_S${SEASON_NUMBER}_E${EPISODE_NUMBER}_${OPT_LANG}.mp4"
 	[ -e "$OUTFILE" ] && echo "Already downloaded Season ${SEASON_NUMBER} Episode ${EPISODE_NUMBER}" && return
-    local URL=$(get_episode "$SEASON_NUMBER" "$EPISODE_NUMBER")
+	local URL="$(get_episode "$SEASON_NUMBER" "$EPISODE_NUMBER")"
 	[ -z "$URL" ] && echo "Unable to download Season ${SEASON_NUMBER} Episode ${EPISODE_NUMBER}; skipping" && return
 	p_info "Downloading Season $SEASON_NUMBER Episode $EPISODE_NUMBER ($URL)"
+	if [ -z "$OPT_DRY" ]; then
 	trap download_interrupt SIGINT
-    TMPDIR=$(mktemp -d "/tmp/southparkdownloader.XXXXXXXXXX")
+	TMPDIR="$(mktemp -d "/tmp/southparkdownloader.XXXXXXXXXX")"
 	[ -n "$OPT_PROGRESS" ] && monitor_progress "$TMPDIR"&
 	pushd "$TMPDIR" > /dev/null
 	if ! "$YOUTUBE_DL" "$URL" 2>/dev/null | grep --line-buffered "^\[download\]" | grep -v --line-buffered "^\[download\] Destination:"; then
@@ -189,20 +194,21 @@ download_episode() {
 	ffmpeg -safe 0 -f concat -i "list.txt" -c copy "$OUTFILE" 2>/dev/null
 	popd > /dev/null
 	trap - SIGINT
+	fi
 	tmp_cleanup
 }
 
 # Takes season number as an argument
 download_season() {
 	local SEASON_NUMBER="$1"
-    local NUM_EPISODES=$(get_num_episodes "$SEASON_NUMBER")
+	local NUM_EPISODES="$(get_num_episodes "$SEASON_NUMBER")"
 	for i in $(seq "$NUM_EPISODES"); do
 		download_episode "$SEASON_NUMBER" "$i"
 	done
 }
 
 download_all() {
-    local NUM_SEASONS=$(get_num_seasons)
+	local NUM_SEASONS="$(get_num_seasons)"
 	for i in $(seq "$NUM_SEASONS"); do
 		download_season "$i"
 	done