方向键/进入菜单

如何在Shell脚本中创建一个菜单，该菜单将显示3个选项，用户将使用箭头键移动突出显示光标并按Enter选择一个？

对话框是您要实现的理想工具。这是一个简单的三选菜单的示例：

dialog --menu "Choose one:" 10 30 3 \
    1 Red \
    2 Green \
    3 Blue

语法如下：

dialog --menu <text> <height> <width> <menu-height> [<tag><item>]

选择内容将发送到stderr。这是使用3种颜色的示例脚本。

#!/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

在Debian上，您可以dialog通过具有相同名称的软件包进行安装。

这是函数bash形式的纯脚本解决方案select_option，仅依赖于ANSI转义序列和内置函数read。

在OSX上的Bash 4.2.45上工作。据我所知，时髦的部分可能无法在所有环境中正常工作，它们是get_cursor_row()，key_input()（用于检测上/下键）和cursor_to()功能。

#!/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
}

这是一个示例用法：

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]}"

输出如下所示，当前选择的选项使用反色反色突出显示（在markdown中难以传达）。print_selected()如果需要，可以在功能中进行调整。

Select one option using up/down keys and enter to confirm:

  [one] 
   two 
   three 

更新：这是一个扩展select_opt了上述select_option功能的扩展，使它易于在case语句中使用：

function select_opt {
    select_option "$@" 1>&2
    local result=$?
    echo $result
    return $result
}

具有3个文字选项的用法示例：

case `select_opt "Yes" "No" "Cancel"` in
    0) echo "selected Yes";;
    1) echo "selected No";;
    2) echo "selected Cancel";;
esac

如果存在某些已知条目（在这种情况下为“是”和“否”），您还可以混合使用，并$?在通配符情况下利用退出代码：

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