方向键/进入菜单

Question

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？

Answer 1

这是函数bash形式的纯脚本解决方案select_option，完全依赖于ANSI 转义序列和内置的read.

适用于 OSX 上的 Bash 4.2.45。据我所知get_cursor_row()，在所有环境中可能无法在所有环境中同样有效地工作的时髦部分是, key_input()（检测向上/向下键）和cursor_to()函数。

#!/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向 ansi 着色突出显示（这里很难在 Markdown 中表达）。print_selected()如果需要，这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select_opt包装上述select_option函数的小扩展，使其易于在case语句中使用：

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

使用 3 个文字选项的示例用法：

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

如果有一些已知条目（在这种情况下是和否），您还可以混合使用，并利用$?通配符案例的退出代码：

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

Answer 2

问题仅涉及一项选择。
\n如果你正在寻找一个多选菜单，这里是它的纯 bash实现：

\n

\n

使用
\n j/k或\xe2\x86\x91/\xe2\x86\x93箭头键向上或向下导航
\n \xe2\x8e\xb5（空格）切换选择，
\n \xe2\x8f\x8e（Enter）确认选择。

\n

可以这样调用：

\n

my_options=(   "Option 1"  "Option 2"  "Option 3" )\npreselection=( "true"      "true"      "false"    )\n\nmultiselect result my_options preselection\n

\n

该multiselect函数的最后一个参数是可选的，可用于预先选择某些选项。

\n

结果将作为数组存储在multiselect作为第一个参数传递的变量中。这是将选项与结果结合起来的示例：

\n

idx=0\nfor option in "${my_options[@]}"; do\n    echo -e "$option\\t=> ${result[idx]}"\n    ((idx++))\ndone\n

\n

\n

function multiselect {\n    # little helpers for terminal print control and key input\n    ESC=$( printf "\\033")\n    cursor_blink_on()   { printf "$ESC[?25h"; }\n    cursor_blink_off()  { printf "$ESC[?25l"; }\n    cursor_to()         { printf "$ESC[$1;${2:-1}H"; }\n    print_inactive()    { printf "$2   $1 "; }\n    print_active()      { printf "$2  $ESC[7m $1 $ESC[27m"; }\n    get_cursor_row()    { IFS=\';\' read -sdR -p $\'\\E[6n\' ROW COL; echo ${ROW#*[}; }\n\n    local return_value=$1\n    local -n options=$2\n    local -n defaults=$3\n\n    local selected=()\n    for ((i=0; i<${#options[@]}; i++)); do\n        if [[ ${defaults[i]} = "true" ]]; then\n            selected+=("true")\n        else\n            selected+=("false")\n        fi\n        printf "\\n"\n    done\n\n    # determine current screen position for overwriting the options\n    local lastrow=`get_cursor_row`\n    local startrow=$(($lastrow - ${#options[@]}))\n\n    # ensure cursor and input echoing back on upon a ctrl+c during read -s\n    trap "cursor_blink_on; stty echo; printf \'\\n\'; exit" 2\n    cursor_blink_off\n\n    key_input() {\n        local key\n        IFS= read -rsn1 key 2>/dev/null >&2\n        if [[ $key = ""      ]]; then echo enter; fi;\n        if [[ $key = $\'\\x20\' ]]; then echo space; fi;\n        if [[ $key = "k" ]]; then echo up; fi;\n        if [[ $key = "j" ]]; then echo down; fi;\n        if [[ $key = $\'\\x1b\' ]]; then\n            read -rsn2 key\n            if [[ $key = [A || $key = k ]]; then echo up;    fi;\n            if [[ $key = [B || $key = j ]]; then echo down;  fi;\n        fi \n    }\n\n    toggle_option() {\n        local option=$1\n        if [[ ${selected[option]} == true ]]; then\n            selected[option]=false\n        else\n            selected[option]=true\n        fi\n    }\n\n    print_options() {\n        # print options by overwriting the last lines\n        local idx=0\n        for option in "${options[@]}"; do\n            local prefix="[ ]"\n            if [[ ${selected[idx]} == true ]]; then\n              prefix="[\\e[38;5;46m\xe2\x9c\x94\\e[0m]"\n            fi\n\n            cursor_to $(($startrow + $idx))\n            if [ $idx -eq $1 ]; then\n                print_active "$option" "$prefix"\n            else\n                print_inactive "$option" "$prefix"\n            fi\n            ((idx++))\n        done\n    }\n\n    local active=0\n    while true; do\n        print_options $active\n\n        # user key control\n        case `key_input` in\n            space)  toggle_option $active;;\n            enter)  print_options -1; break;;\n            up)     ((active--));\n                    if [ $active -lt 0 ]; then active=$((${#options[@]} - 1)); fi;;\n            down)   ((active++));\n                    if [ $active -ge ${#options[@]} ]; then active=0; fi;;\n        esac\n    done\n\n    # cursor position back to normal\n    cursor_to $lastrow\n    printf "\\n"\n    cursor_blink_on\n\n    eval $return_value=\'("${selected[@]}")\'\n}\n

\n

信用：这个 bash 函数是Denis Semenenko 实现的定制版本。

\n

Answer 3

对话是您要实现的目标的绝佳工具。这是一个简单的 3 选项菜单示例：

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通过同名的软件包进行安装。