Shell Script - Function - Selection

前言

Shell Script也能做出上下選單

function

基本上這個功能是利用function功能刻出來的，我也是找到後複製修改而已

function code

參考資料

shell - Arrow key/Enter menu - Unix & Linux Stack Exchange

select_option

#!/usr/bin/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
}

select_opt - 更容易在case中使用

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

應用方法

select_option用法

code

...
# 已經有function select_option前提
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]}"

效果

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

  [one] 
   two 
   three 

select_opt

Code

...
# 在有function select_option & select_opt前提下

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

效果

[selected Yes]
selected No
selected Cancel

利用ls/cat等指令搭配select_opt製作選單

舉例：選擇目錄A,B,C作為選單

前提:目錄A,B,C的名字是會變動的(Eg:自動依照日期備份後會建立日期目錄)

[kiwi]$> ls /storage/backup
--------------------------------------------------------------
2025-03-24  2025-03-25

已知預設我的script會移除超過5天的備份, 所以可以假設最大的目錄數量為5

# 在script中建立變數
# Vars
DATE1=$(ls /storage/backup/ | sed -n '1p')
DATE2=$(ls /storage/backup/ | sed -n '2p')
DATE3=$(ls /storage/backup/ | sed -n '3p')
DATE4=$(ls /storage/backup/ | sed -n '4p')
DATE5=$(ls /storage/backup/ | sed -n '5p')

# 利用變數建立select_opt選單
case `select_opt "$DATE1" "$DATE2" "$DATE3" "$DATE4" "$DATE5" "Exit"` in
    0) echo "$DATE1" is choosen" ;;
    1) echo "$DATE2" is choosen" ;;
    2) echo "$DATE3" is choosen" ;;
    3) echo "$DATE4" is choosen" ;;
    4) echo "$DATE5" is choosen" ;;
    5) exit ;;
esac

效果

[2025-03-24]
 2025-03-25
 
 
 
 Exit

設定的範圍大於實際目錄的數字的時候會有空白的選項