Arrow key/Enter menu
Here is a pure bash
script solution in form of the select_option
function, relying solely on ANSI escape sequences and the built-in read
.
Works on Bash 4.2.45 on OSX. The funky parts that might not work equally well in all environments from all I know are the get_cursor_row()
, key_input()
(to detect up/down keys) and the cursor_to()
functions.
#!/usr/bin/env bash
# Renders a text based list of options that can be selected by the
# user using up, down and enter keys and returns the chosen option.
#
# Arguments : list of options, maximum of 256
# "opt1" "opt2" ...
# Return value: selected index (0 for opt1, 1 for opt2 ...)
function select_option {
# little helpers for terminal print control and key input
ESC=$( printf "\033")
cursor_blink_on() { printf "$ESC[?25h"; }
cursor_blink_off() { printf "$ESC[?25l"; }
cursor_to() { printf "$ESC[$1;${2:-1}H"; }
print_option() { printf " $1 "; }
print_selected() { printf " $ESC[7m $1 $ESC[27m"; }
get_cursor_row() { IFS=';' read -sdR -p $'\E[6n' ROW COL; echo ${ROW#*[}; }
key_input() { read -s -n3 key 2>/dev/null >&2
if [[ $key = $ESC[A ]]; then echo up; fi
if [[ $key = $ESC[B ]]; then echo down; fi
if [[ $key = "" ]]; then echo enter; fi; }
# initially print empty new lines (scroll down if at bottom of screen)
for opt; do printf "\n"; done
# determine current screen position for overwriting the options
local lastrow=`get_cursor_row`
local startrow=$(($lastrow - $#))
# ensure cursor and input echoing back on upon a ctrl+c during read -s
trap "cursor_blink_on; stty echo; printf '\n'; exit" 2
cursor_blink_off
local selected=0
while true; do
# print options by overwriting the last lines
local idx=0
for opt; do
cursor_to $(($startrow + $idx))
if [ $idx -eq $selected ]; then
print_selected "$opt"
else
print_option "$opt"
fi
((idx++))
done
# user key control
case `key_input` in
enter) break;;
up) ((selected--));
if [ $selected -lt 0 ]; then selected=$(($# - 1)); fi;;
down) ((selected++));
if [ $selected -ge $# ]; then selected=0; fi;;
esac
done
# cursor position back to normal
cursor_to $lastrow
printf "\n"
cursor_blink_on
return $selected
}
Here is an example usage:
echo "Select one option using up/down keys and enter to confirm:"
echo
options=("one" "two" "three")
select_option "${options[@]}"
choice=$?
echo "Choosen index = $choice"
echo " value = ${options[$choice]}"
Output looks like below, with the currently selected option highlighted using inverse ansi coloring (hard to convey here in markdown). This can be adapted in the print_selected()
function if desired.
Select one option using up/down keys and enter to confirm:
[one]
two
three
Update: Here is a little extension select_opt
wrapping the above select_option
function to make it easy to use in a case
statement:
function select_opt {
select_option "$@" 1>&2
local result=$?
echo $result
return $result
}
Example usage with 3 literal options:
case `select_opt "Yes" "No" "Cancel"` in
0) echo "selected Yes";;
1) echo "selected No";;
2) echo "selected Cancel";;
esac
You can also mix if there are some known entries (Yes and No in this case), and leverage the exit code $?
for the wildcard case:
options=("Yes" "No" "${array[@]}") # join arrays to add some variable array
case `select_opt "${options[@]}"` in
0) echo "selected Yes";;
1) echo "selected No";;
*) echo "selected ${options[$?]}";;
esac
dialog is a great tool for what you are trying to achieve. Here's the example of a simple 3-choices menu:
dialog --menu "Choose one:" 10 30 3 \
1 Red \
2 Green \
3 Blue
The syntax is the following:
dialog --menu <text> <height> <width> <menu-height> [<tag><item>]
The selection will be sent to stderr
. Here's a sample script using 3 colors.
#!/bin/bash
TMPFILE=$(mktemp)
dialog --menu "Choose one:" 10 30 3 \
1 Red \
2 Green \
3 Blue 2>$TMPFILE
RESULT=$(cat $TMPFILE)
case $RESULT in
1) echo "Red";;
2) echo "Green";;
3) echo "Blue";;
*) echo "Unknown color";;
esac
rm $TMPFILE
On Debian, you can install dialog
through the package of the same name.