循环 Bash Shell 脚本

Question

我对 linux 非常陌生，我编写了一个简单的 bash shell 脚本，它要求用户输入一个数字，然后要求另一个数字并显示数字的总和和乘积。我对此没有任何问题，但我想循环脚本。

例如，我想询问用户是否要退出，如果他们选择不退出，脚本会重新开始并再次询问两个数字。如果有谁知道循环的东西，你能帮我吗？谢谢。

这是我的代码：

#!/bin/bash


echo -n "Name please? "
read name
echo "enter a number."
read number1
echo "enter another number"
read number2
echo "Thank you $name"
let i=0
let i=$number1+$number2
let x=0 
let x=$number1*$number2
echo "The sum of the two numbers is: $i"
echo "The product of the two numbers is: $x"
echo "Would you like to quit? Y/N? "
quit=N
while [ "$quit" = "Y" ]
do 
  clear  
  while ["$quit" != "Y" ]
  do
    echo "enter a number."
    read number1
    echo "enter another number"
    read number2
    echo "Thank you $name"
    let i=0
    let i=$number1+$number2
    let x=0 
    let x=$number1*$number2
    echo "The sum of the two numbers is: $i"
    echo "The product of the two numbers is: $x"
    echo "Would you like to quit? Y/N? "

Answer 1

#!/bin/bash

# Initialize quit so we enter the outer loop first time
quit="N"

# Loop while quit is N
while [ "$quit" = "N" ]
do
  echo -n "Name please? "
  read name
  echo "enter a number."
  read number1
  echo "enter another number"
  read number2
  echo "Thank you $name"
  let i=0
  let i=$number1+$number2
  let x=0 
  let x=$number1*$number2
  echo "The sum of the two numbers is: $i"
  echo "The product of the two numbers is: $x"

#reset quit - so we enter the inner loop first time
  quit="" 

#we want to repeat until quit is Y or N: 
#while quit is not "Y" and quit is not "N"
  while [ "$quit" != "Y" -a "$quit" != "N" ]
  do
    echo "Would you like to quit? Y/N?"
    read quit

#Convert lower case y/n to Y/N
    quit=`echo $quit | tr yn YN`
  done
done

Answer 2

while [[ "$(read -p "Quit?" q;echo $q)" != "y" ]] ; do
    echo okay, go on
done

Answer 3

这是一个循环的简单示例：

#!/bin/env bash
let quit="N"
while [ $quit != "Y" ]; do
    echo "To quit, enter Y:"
    read quit
done

Answer 4

#!/bin/bash
function sumAndProd {
    read -p "enter a number: " number1
    read -p "enter another number: " number2
    echo "Thank you $name"

    sum=$((number1+number2))
    prod=$((number1*$number2))

    echo "The sum of the two numbers is: $sum"
    echo "The product of the two numbers is: $prod"
}

read -p "Name please? " name

quit=N
while [[ "$quit" != Y ]]
do 
    sumAndProd
    read -p "Would you like to quit? Y/N? " quit  
done

这更像是一次代码审查。

• 主要是将重复的部分放在一个函数中。
• 您最好使用富有表现力的名称，而不是 i、x，可以缩写为 sum 和 prod。
• 如果你在一个赋值(let a=0) 后面加上一个赋值，而之前没有使用你的变量，那么第一个赋值是没有意义的。
• 用户名不会改变 - 我们只需要请求一次。
• while (cond) ; do {block} done# 是循环的一种形式。
• 您可以使用 read 指定一个提示符 (-p)，因此它将以一行而不是两行结束。
• 就其本身而言，您不会经常找到let。对于算术表达式，x=$((expression)) 更为常见。
• 由于您不重复使用 sum 和 prod，因此您甚至不需要变量。只需echo The sum is $((number1+number2))

Answer 5

最简单的做法是永远循环并在用户退出时中断：

while true
do
    read -p "Continue to loop? " answer
    [ "n" = "$answer" ] && break
done
echo "Now I'm here!"

break 命令使您跳出当前循环并在循环之后继续。不需要标志变量。

顺便说一句：

[ "n" = "$answer" ] && break

等同于：

if [ "n" = "$answer" ]
then
    break
fi

注意-p 用于read 命令中的提示。这样，您可以同时提示和读取变量。您还可以在 echo 语句中使用 \c 来抑制换行，或者使用不执行 NL 的 printf：

read -p "What do you want? " wants   #Prompt on the same line as the read

echo "What are your desires? \c"     #Prompt on the same line as the read
read desires

printf "What are your hopes? "       #Prompt on the same line as the read
read hopes

希望这会有所帮助。

Answer 6

#!/bin/sh
while true
do
 /var/www/bash/grep_ffmpeg.sh
 sleep 15
done

使用 nohup 循环