Bash：如果未提供參數，則顯示提示

同時支持腳本提示和參數的最佳方式是什麼？如果未提供參數，我想顯示提示。

有沒有比這更好/更短的東西？⇩

PROJECT_DIR=$1
SITE_NAME=$2
ADMIN_PWD=$3
THEME_DIR=$4
THEME_NAME=$5

if [ -z "${PROJECT_DIR}" ]; then
   echo "Directory where project resides:"
   read PROJECT_DIR
fi

if [ -z "${SITE_NAME}" ]; then
   echo "Name of the website:"
   read SITE_NAME
fi

if [ -z "${ADMIN_PWD}" ]; then
   echo "Admin password:"
   read ADMIN_PWD
fi

if [ -z "${THEME_DIR}" ]; then
   echo "Directory of the theme:"
   read THEME_DIR
fi

if [ -z "${THEME_NAME}" ]; then
   echo "Name of the theme:"
   read THEME_NAME
fi

您可以使用函式將其縮短一點：

#!/bin/bash

ask()
{
 declare -g $1="$2"
 if [ -z "${!1}" ]; then
   echo "$3"
   read $1
 fi
}

ask PROJECT_DIR "$1" "Directory where project resides:"
ask SITE_NAME   "$2" "Name of the website:"
ask ADMIN_PWD   "$3" "Admin password:"
ask THEME_DIR   "$4" "Directory of the theme:"
ask THEME_NAME  "$5" "Name of the theme:"

echo "$PROJECT_DIR $SITE_NAME"

雖然這需要bash並且不會在sh.

您可以使用參數擴展來做到這一點${variable:-default}

例如：

function get_value_as_arg_or_prompt() {
 value=${1:-$(read -p "Enter: " x && echo "$x")}
 echo "$value"
}

如果給出一個論點：

$ get_value_as_arg_or_prompt "Hi there"
Hi there

如果不給出論點：

$ get_value_as_arg_or_prompt
Enter: I'm here
I'm here

引用自：https://unix.stackexchange.com/questions/110680