diff --git a/README.md b/README.md
index d2d17bc..e51340c 100644
--- a/README.md
+++ b/README.md
@@ -66,6 +66,14 @@ Put `set -g @open 'x'` in `tmux.conf`.
 
 Put `set -g @open-editor 'C-x'` in `tmux.conf`.
 
+> How can I change the default editor without setting `$EDITOR`?
+
+Put `set -g @open-editor-command 'my-editor'` in `tmux.conf`.
+
+> How can I change the default command for opening the selection?
+
+Put `set -g @open-opener-command 'my-opener'` in `tmux.conf`.
+
 > How can I change the default search engine to "duckduckgo" or any other one?
 
 Put `set -g @open-S 'https://www.duckduckgo.com/'` in `tmux.conf`
diff --git a/open.tmux b/open.tmux
index 824ea24..517cdd1 100755
--- a/open.tmux
+++ b/open.tmux
@@ -2,6 +2,7 @@
 
 CURRENT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
+# shellcheck source=./scripts/helpers.sh
 source "$CURRENT_DIR/scripts/helpers.sh"
 
 default_open_key="o"
@@ -11,29 +12,21 @@ default_open_editor_key="C-o"
 open_editor_option="@open-editor"
 open_editor_override="@open-editor-command"
 
+open_opener_override="@open-opener-command"
+
 command_exists() {
 	local command="$1"
 	type "$command" >/dev/null 2>&1
 }
 
 is_osx() {
-	local platform=$(uname)
-	[ "$platform" == "Darwin" ]
+	[ "$(uname)" == "Darwin" ]
 }
 
 is_cygwin() {
 	[[ "$(uname)" =~ CYGWIN ]]
 }
 
-get_editor_from_the_env_var() {
-	if [ -z $EDITOR ]; then
-		# $EDITOR not set, fallback
-		echo "vi"
-	else
-		echo "$EDITOR"
-	fi
-}
-
 command_generator() {
 	local command_string="$1"
 	echo "xargs -I {} tmux run-shell -b 'cd #{pane_current_path}; $command_string \"{}\" > /dev/null'"
@@ -47,12 +40,15 @@ search_command_generator() {
 }
 
 generate_open_command() {
-	if is_osx; then
-		echo "$(command_generator "open")"
+  local opener
+  if opener="$(get_tmux_option "$open_opener_override" '')" && [ -n "${opener-}" ]; then
+    command_generator "${opener}"
+	elif is_osx; then
+		command_generator "open"
 	elif is_cygwin; then
-		echo "$(command_generator "cygstart")"
+		command_generator "cygstart"
 	elif command_exists "xdg-open"; then
-		echo "$(command_generator "xdg-open")"
+		command_generator "xdg-open"
 	else
 		# error command for Linux machines when 'xdg-open' not installed
 		"$CURRENT_DIR/scripts/tmux_open_error_message.sh" "xdg-open"
@@ -61,12 +57,15 @@ generate_open_command() {
 
 generate_open_search_command() {
 	local engine="$1"
-	if is_osx; then
-		echo "$(search_command_generator "open" "$engine")"
+	local opener
+	if opener="$(get_tmux_option "$open_opener_override" '')" && [ -n "${opener-}" ]; then
+		search_command_generator "$opener" "$engine"
+	elif is_osx; then
+		search_command_generator "open" "$engine"
 	elif is_cygwin; then
-		echo "$(command_generator "cygstart")"
+		command_generator "cygstart"
 	elif command_exists "xdg-open"; then
-		echo "$(search_command_generator "xdg-open" "$engine")"
+		search_command_generator "xdg-open" "$engine"
 	else
 		# error command for Linux machines when 'xdg-open' not installed
 		"$CURRENT_DIR/scripts/tmux_open_error_message.sh" "xdg-open"
@@ -76,16 +75,19 @@ generate_open_search_command() {
 # 1. write a command to the terminal, example: 'vim -- some_file.txt'
 # 2. invoke the command by pressing enter/C-m
 generate_editor_command() {
-	local environment_editor=$(get_editor_from_the_env_var)
-	local editor=$(get_tmux_option "$open_editor_override" "$environment_editor")
+	local environment_editor="${EDITOR:-vi}"
+	local editor
+	editor=$(get_tmux_option "$open_editor_override" "$environment_editor")
 	# vim freezes terminal unless there's the '--' argument. Other editors seem
 	# to be fine with it (textmate [mate], light table [table]).
 	echo "xargs -I {} tmux send-keys '$editor -- \"{}\"'; tmux send-keys 'C-m'"
 }
 
 set_copy_mode_open_bindings() {
-	local open_command="$(generate_open_command)"
-	local key_bindings=$(get_tmux_option "$open_option" "$default_open_key")
+	local open_command
+	open_command="$(generate_open_command)"
+	local key_bindings
+	key_bindings=$(get_tmux_option "$open_option" "$default_open_key")
 	local key
 	for key in $key_bindings; do
 		if tmux-is-at-least 2.4; then
@@ -99,8 +101,10 @@ set_copy_mode_open_bindings() {
 }
 
 set_copy_mode_open_editor_bindings() {
-	local editor_command="$(generate_editor_command)"
-	local key_bindings=$(get_tmux_option "$open_editor_option" "$default_open_editor_key")
+	local editor_command
+	editor_command="$(generate_editor_command)"
+	local key_bindings
+	key_bindings="$(get_tmux_option "$open_editor_option" "$default_open_editor_key")"
 	local key
 	for key in $key_bindings; do
 		if tmux-is-at-least 2.4; then
@@ -114,13 +118,14 @@ set_copy_mode_open_editor_bindings() {
 }
 
 set_copy_mode_open_search_bindings() {
-	local stored_engine_vars="$(stored_engine_vars)"
+	local stored_engine_vars
+	stored_engine_vars="$(stored_engine_vars)"
 	local engine_var
 	local engine
 	local key
 
 	for engine_var in $stored_engine_vars; do
-		engine="$(get_engine "$engine_var")"
+		engine="$(get_engine "$engine_var")" || continue
 
 		if tmux-is-at-least 2.4; then
 			tmux bind-key -T copy-mode-vi "$engine_var" send-keys -X copy-pipe-and-cancel "$(generate_open_search_command "$engine")"
diff --git a/scripts/helpers.sh b/scripts/helpers.sh
index 9dc984c..ae06e05 100644
--- a/scripts/helpers.sh
+++ b/scripts/helpers.sh
@@ -1,12 +1,9 @@
 get_tmux_option() {
 	local option="$1"
 	local default_value="$2"
-	local option_value=$(tmux show-option -gqv "$option")
-	if [ -z "$option_value" ]; then
-		echo "$default_value"
-	else
-		echo "$option_value"
-	fi
+	local option_value
+	option_value="$(tmux show-option -gqv "$option")"
+	echo "${option_value:-$default_value}"
 }
 
 # Ensures a message is displayed for 5 seconds in tmux prompt.
@@ -22,7 +19,8 @@ display_message() {
 	fi
 
 	# saves user-set 'display-time' option
-	local saved_display_time=$(get_tmux_option "display-time" "750")
+	local saved_display_time
+	saved_display_time="$(get_tmux_option "display-time" "750")"
 
 	# sets message display time to 5 seconds
 	tmux set-option -gq display-time "$display_duration"
@@ -37,7 +35,7 @@ display_message() {
 stored_engine_vars() {
 	tmux show-options -g |
 		grep -i "^@open-" |
-		grep -vi "^@open-editor" |
+		grep -Evi "^@open-(editor|opener)" |
 		cut -d '-' -f2 |
 		cut -d ' ' -f1 |
 		xargs
@@ -48,15 +46,15 @@ get_engine() {
 	tmux show-options -g | grep -i "^@open-$engine_var" | cut -d ' ' -f2 | xargs
 }
 
-tmux_version="$(tmux -V | cut -d ' ' -f 2 | sed 's/next-//'))"
+# The last grep is required to remove non-digits from version such as "3.0a".
+tmux_version="$(tmux -V | cut -d ' ' -f 2 | grep -Eo '[0-9\.]+')"
 tmux-is-at-least() {
-	if [[ $tmux_version == $1 ]]
-	then
+	if [[ $tmux_version == "$1" ]]; then
 		return 0
 	fi
 
-	local IFS=.
-	local i tver=($tmux_version) wver=($1)
+	IFS='.' read -r -a tver <<< "$tmux_version"
+	IFS='.' read -r -a wver <<< "$1"
 
 	# fill empty fields in tver with zeros
 	for ((i=${#tver[@]}; i<${#wver[@]}; i++)); do