Question

第一篇文章。提前感谢您的所有帮助。

这是我试图编写的基本脚本，它将改变CentOS系统的DNS设置（/etc/resolv.conf）。该脚本应该执行以下操作：

获取DNS1
询问是否有其他DNS
- 如果是，请转到＃3（获取DNS2）
- 如果不是，请使用一个DNS条目写“/etc/resolv.conf”。
获取DNS2
询问是否有其他DNS
- 如果是，请转到＃5（获取DNS3）
- 如果不是，请只用两个DNS条目写'/etc/resolv.conf'。
获取DNS3
回显DNS1 DNS2 DNS3，并询问它们是否正确
- 如果是，请使用所有三个DNS条目写入“/etc/resolv.conf”。
- 如果不是，请重新开始。（此部分尚未编写）

此脚本正确获取DNS1，询问是否有其他DNS。如果不是，则正确写入文件。如果不是，它会继续询问DNS2。

这是它不再有效的地方。在读取DNS2后，它不会继续使用脚本来提示是否有其他DNS。它冻结了。如果你能在这个过程中看到错误，请告诉我。

    #!/bin/bash

    # FUNCTION TO GRAB THE FIRST DNS
    oneDNS()
    {
      read -p "Enter DNS:   (looks like 123.231.132.1)      " firstDNS
    }

    # FUNCTION TO GRAB THE SECOND DNS
    twoDNS()
    {
      read -p "Enter second DNS:    (looks like 123.231.132.2)      " secondDNS
    }

    # FUNCTION TO GRAB THE THIRD DNS
    threeDNS()
    {
      read -p "Enter third DNS:     (looks like 123.321.132.3)      " thirdDNS
    }

    # FUNCTION WHICH WRITE /etc/resolv.conf IF ONLY
    writeOneResolveFile()
    {
    cat << EOF > $1
    nameserver $firstDNS
    EOF
    #don't use any space before of after 'EOF' in the previous line

      echo ""
      echo "Your informatons was saved in '$1' file."
      echo ""
      exit 0
    }

    writeTwoResolveFile()
    {
    cat << EOF > $1
    nameserver $firstDNS
    nameserver $secondDNS
    EOF
    #don't use any space before of after 'EOF' in the previous line

      echo ""
      echo "Your informatons was saved in '$1' file."
      echo ""
      exit 0
    }

    writeThreeResolveFile()
    {
    cat << EOF > $1
    nameserver $firstDNS
    nameserver $secondDNS
    nameserver $thirdDNS
    EOF
    #don't use any space before of after 'EOF' in the previous line

      echo ""
      echo "Your information was saved in '$1' file."
      echo ""
      exit 0
    }

    file="/etc/resolv.conf"
    if [ ! -f $file ]; then
      echo ""
      echo "The file '$file' doesn't exist!"
      echo ""
      exit 1
    fi

    clear
    echo "Let's set up the DNS your server"

    echo ""
    oneDNS
    echo ""
    echo "So DNS settings are:"
    echo "DNS Address is: $firstDNS"
    echo "Do you have another DNS? [y/n]: "
    while true; do
       read yn
       case $yn in
         [Yy]* ) twoDNS;;
         [Nn]* ) writeOneResolveFile $file;;
             * ) echo "Please enter y or n!";;
       esac
    done

    echo ""
    echo "So DNS settings are:"
    echo "First DNS Address is:  $firstDNS"
    echo "Second DNS Address is: $secondDNS"
    echo "Do you have another DNS? [y/n]: "
    while true; do
       read yn
       case $yn in
         [Yy]* ) threeDNS;;
         [Nn]* ) writeTwoResolveFile $file;;
             * ) echo "Please enter y or n!";;
       esac
    done

    echo ""
    echo "So DNS settings are:"
    echo "First DNS Address is: $firstDNS"
    echo "Second DNS Address is: $secondDNS"
    echo "Third DNS Address is: $thirdDNS"

    echo "Is this information correct? [y/n]: "
    while true; do
       read yn
       case $yn in
         [Yy]* ) writeThreeResolveFile $file;;
         [Nn]* ) ;;
             * ) echo "Please enter y or n!";;
       esac
    done

再次，非常感谢任何帮助。

感谢。

卡姆兰

Answer 1

仔细检查你的引号，你在第93行末尾错过了一个。

Answer 2

问题是，在询问“oneDNS”之后，你进入一个无限循环，你要求“twoDNS”。从这个循环你永远逃脱。亲自尝试一下：
对于调试模式，您可能希望将第一行更改为#!/bin/bash -x。

echo ""
oneDNS
echo ""
echo "So DNS settings are:"
echo "DNS Address is: $firstDNS"
echo "Do you have another DNS? [y/n]: "
while true; do       #<-- how are you planning to escape from this ??
   read yn
   case $yn in
     [Yy]* ) twoDNS;;      #<-- this will be asked over and over again 
     [Nn]* ) writeOneResolveFile $file;;
         * ) echo "Please enter y or n!";;
   esac
done

Answer 3

你的循环有while true，没有什么可以突破无限循环。您需要指定退出条件。事情的方式，它只是再次要求yn提示（第二次和随后的时间没有任何提示）。

更好的设计可能类似于

servers=
another=true
while $another; do
    read -p "DNS server address to add?" server
    servers="$servers $server"
    case $dns in
      '') ;;
      *) while true; do
           read -p "Add another [yn]?" yn
           case $yn in [Yy]*) break;; [Nn]*) another=false; break;; esac
         done ;;
    esac
done

for s in $servers; do
   echo nameserver $s
done >/etc/resolv.conf

（未经测试，但希望至少可以提出一些改变。）

Bash脚本：多个问题/输入问题

感谢。

3 个答案: