Question

我可以使用一些帮助来弄清楚以下脚本中的省略号为什么不起作用。 if的第一部分有效，而语句的else部分有效，而elif无效。换句话说，当我以“ root”身份登录时，会得到我期望的DNS地址。如果我以Guest身份登录，则可以获得我期望的DNS地址，但如果我以elif中列出的任何学生身份登录，则不会。

#!/bin/bash

\# Setting DNS by User

\# Get variables. $3 is logging in user.
user=$3

\# Root and Admin should be wide open

if [ $user = "root" ] || [ $user = "admin" ]; then
networksetup -setdnsservers Wi-Fi 8.8.8.8
networksetup -setdnsservers Ethernet 8.8.8.8

\# Older students get an open, but filtered experience:

elif 

\# Adams class
[ $user = "Student01" ] || 
[ $user = "Student02" ] || 
[ $user = "Student03" ] ||
[ $user = "Student04" ] ||

\# Mariannes class:
[ $user = "Student05" ] ||
[ $user = "Student06" ] ||
[ $user = "Student07" ] ||
[ $user = "Student08" ]   

then
networksetup -setdnsservers Wi-Fi 8.8.4.4
networksetup -setdnsservers Ethernet 8.8.4.4

\# Everyone else gets whitelisted DNS

else
networksetup -setdnsservers Wi-Fi 208.67.222.222
networksetup -setdnsservers Ethernet 208.67.222.222

fi

exit 0

Answer 1

我的第一个想法是，这实际上不是一种可维护的方法。这是我认为）不是使用if / elif / if / fi结构的方式。

也就是说，我将向您抛出一些高级脚本，该脚本将执行以下操作您想要的并且更受支持。

首先，我建议在bash数组中保留管理员和学生的姓名。最终，您可以从其他来源（例如文件：注释）。如图所示，这将使if / elif测试更加简单。

#! /usr/bin/env bash

# Setting DNS by User

# Get variables. $3 is logging in user.
user=$3

# admin_list=$HOME/admin.list
# declare -a admins
# if [[ -f "$admin_list" ]] ; then
#     IFS=$'\n' read -d '' -r -a admins < <(sed -e 's/#.*$//' "$admin_list")
# 
#     wait $! || return $?
# else
#     echo "$admin_list not found: skipping"
# fi

declare -a admins=( root admin )

# special_list=$HOME/special.list
# declare -a special
# if [[ -f "$special_list" ]] ; then
#     IFS=$'\n' read -d '' -r -a special < <(sed -e 's/#.*$//' "$special_list")
# 
#     wait $! || return $?
# else
#     echo "$special_list not found: skipping"
# fi

declare -a special=(

# Adams class
"Student01"
"Student02"
"Student03"
"Student04"

# Mariannes class:
"Student05"
"Student06"
"Student07"
"Student08"

)

# Root and Admin should be wide open

if [[ " ${admins[@]} " =~ " $user " ]] ; then

    echo Admin

    # networksetup -setdnsservers Wi-Fi 8.8.8.8
    # networksetup -setdnsservers Ethernet 8.8.8.8

elif [[ " ${special[@]} " =~ " $user " ]] ; then

    # Older students get an open, but filtered experience:
    # Adams class

    echo Special

    # networksetup -setdnsservers Wi-Fi 8.8.4.4
    # networksetup -setdnsservers Ethernet 8.8.4.4

else

    echo "Everyone else"
    # Everyone else gets whitelisted DNS

    # networksetup -setdnsservers Wi-Fi 208.67.222.222
    # networksetup -setdnsservers Ethernet 208.67.222.222

fi

exit 0

注意：我从您的脚本中注释了nerworksetup并添加了回显对于每种测试条件。您可以删除回声线并取消注释网络设置行。

我将其测试为：

$ script a1 a2 root
Admin

$ script a1 a2 Student02
Special

$ script a1 a2 Student1000
Everyone else

我希望这会有所帮助。

Bash脚本Elif不触发

1 个答案: