Looking for command line package for showing inline text-based menu selector with arrow keys

Question

I'm looking for a tool for displaying inline menus in the shell which can be navigated with arrow-keys and enter. By "inline", I mean that the menu is displayed within the normal flow of stdout text, not in a pop-up dialog on top of everything.

I only found that post trying to address that, but it only mentions either custom scripting or non-inline/pop-up solutions (like dialog or zenity).

What I am looking for is a robust package that I could simply install within a Docker image using apt-get or npm install -g and invoke from my scripts with a list of choices and get back the user's selected item.

In nodeJS, I am using Inquirer which offers not only that kind of menus, but also all sorts of inputs.

Here's an example screenshot of such an inline menu.

The tool does not have to be written in shell script. It can be a binary/script written in any language, as long as it's rather easy to install using apt-get/curl. Even a nodeJS tool would be fine, as long as it's invokable from a shell script to pass it the choices.

Answer 1

A very basic approach to this would be to use bash's select statement; no need to install anything (else). Here's an example I've just got at hand:

#!/bin/bash

[...]

sourceBranch=
targetBranch=
# Force one option per line
columnsBackup=${COLUMNS}
COLUMNS=40

echo "Select source and target branch:"
select branches in \
    "testing -> release-candidate" \
    "release-candidate -> stable-release" \
    "stable-release -> stable"
do
    if [ -z "${branches}" ]; then
        echo "Invalid selection"
        continue
    fi

    sourceBranch="${branches%% -> *}"
    targetBranch="${branches##* -> }"
    break
done

COLUMNS=${columnsBackup}
echo "Releasing from ${sourceBranch} to ${targetBranch}"

[...]

Output:

Select source and target branch:
1) testing -> release-candidate
2) release-candidate -> stable-release
3) stable-release -> stable
#? 1   
Releasing from testing to release-candidate

You'll probably do some case ... esac handling in the do ... done block instead.

Answer 2

I used to use iselect for this, many years ago.

A very basic example:

$ sel="$(iselect -a 'foo' 'bar')"
$ echo $sel
foo

From man iselect:

iSelect is an interactive line selection tool for ASCII files, operating via a full-screen Curses-based terminal session. It can be used either as an user interface frontend controlled by a Bourne-Shell, Perl or other type of script backend as its wrapper or in batch as a pipe filter (usually between grep and the final executing command). In other words: iSelect was designed to be used for any types of interactice line-based selections.

Input Data

Input is read either from the command line (line1 line2 ...) where each argument corresponds to one buffer line or from stdin (when no arguments are given) where the buffer lines are determined according to the newline characters.

You can additionally let substrings displayed in Bold mode for non-selectable lines (because the selectable lines are always displayed bold) by using the construct "<b>"..."</b>" as in HTML.

Answer 3

Here is my take on that question using the bash.

#!/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 ...)


figlet -st "$COLUMNS" "Welcome $USER"
printf '\n?%s\n?%s\n?%s\n\n' "What's the name of your website simple-site" "What's the description of your website(optional):" "Please choose lincense":

# Change the value of options to whatever you want to use.
options=("MIT" "Apache-2.0" "GPL-3.0" "Others")

select_option (){
  # little helpers for terminal print control and key input
  ESC=$(printf '%b' "\033")

  cursor_blink_on() {
    printf '%s' "$ESC[?25h"
  }

  cursor_blink_off() {
    printf '%s' "$ESC[?25l"
  }

  cursor_to() {
    printf '%s' "$ESC[$1;${2:-1}H"
  }

  print_option() {
    printf '   %s ' "$1"
  }

  print_selected() {
    printf '  %s' "$ESC[7m $1 $ESC[27m"
  }

  get_cursor_row() {
    IFS=';' read -sdR -p $'\E[6n' ROW COL; printf '%s' ${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 == $selected ]]; then
         print_selected "$opt"
       else
         print_option "$opt"
       fi
       ((idx++))
     done

     # user key control
     case $(key_input) in
       enter) break;;
       up)    ((selected--));
         if (( $selected < 0 )); then selected=$(($# - 1)); fi;;
         down)  ((selected++));
           if (( selected > $# )); then selected=0; fi;;
         esac
       done

       # cursor position back to normal
       cursor_to $lastrow
       printf "\n"
       cursor_blink_on

       return "$selected"
}


select_option "${options[@]}"
choice=$?

index=$choice
value=${options[$choice]}

case $value in 
  MIT)  ## User selected MIT
   read -rp "Really use? $value [Y/N] " answer
   [[ $answer ]] || { echo "No answer!" >&2; exit 1; }
   if [[ $answer == [Yy] ]]; then
     : ## User selected Y or y, what are you going to do about it?
   elif [[ $answer == [Nn] ]]; then
     : ## User selected N or n what are you going to do about it?
   fi
   printf '%s\n' "You have choosen $answer";;
  Apache-2.0)
   read -rp "Really use? $value [Y/N] " answer
   [[ $answer ]] || { echo "No answer!" >&2; exit 1; }
   if [[ $answer == [Yy] ]]; then
     :
   elif [[ $answer == [Nn] ]]; then
     :
   fi
   ;;
  GPL-3.0)
   read -rp "Really use? $value [Y/N] " answer
   [[ $answer ]] || { echo "No answer!" >&2; exit 1; }
   if [[ $answer == [Yy] ]]; then
     :
   elif [[ $answer == [Nn] ]]; then
     :
   fi
   ;;
  Others)
   read -rp "Really use? $value [Y/N] " answer
   [[ $answer ]] || { echo "No answer!" >&2; exit 1; }
   if [[ $answer == [Yy] ]]; then
     :
   elif [[ $answer == [Nn] ]]; then
     :
   fi
   ;;
esac

The output is more or less what is in the https://i.stack.imgur.com/RO9E5.png The : does nothing which is inside the if statement, Replace : with your code/process or whatever you want to do if the answer is [Yy] or [Nn] That should be enough hand holding to get you started. By the way that code that captures the movement I found posted somewhere I've just expanded/rewrite some syntax.