提问人：P_n 提问时间：8/4/2017 最后编辑：tripleeeP_n 更新时间：11/3/2023 访问量：3650
在 bash 中循环读取，直到给出正确的输入
Looping over read in bash until correct input is given
问：
将命令作为变量传递到提示符的正确方法是什么？例如，我有：
#!/bin/bash
i=`ifconfig tap0 | awk '{print $2}' | egrep "([0-9]{1,3}[\.]){3}[0-9]{1,3}"`
read -p "Enter your IP: " prompt
if [[ $prompt == i ]]
then
echo "Correct IP, congrats"
else
read -p "Wrong IP, try again: " prompt
if [[ $prompt == i ]]
then
echo "Correct IP, congrats"
else
echo "Wrong IP for the second time, exiting."
exit 0
fi
我相信这可以循环，但我不知道如何。
答：
9赞
Eduard Itrich
8/4/2017
#1
只需将您的条件置于一个循环中，即只要您的条件不满足，就会从并要求适当的输入。whilereadstdin
#!/bin/bash
clear
i=$(ifconfig tap0 | awk '{print $2}' | egrep "([0-9]{1,3}[\.]){3}[0-9]{1,3}")
read -p "Enter IP address: " prompt
while [ "$i" != "$prompt" ] ; do
echo "Wrong IP address"
read -p "Enter IP address: " prompt
done
echo "Correct IP, congrats"
如果要在错误输入达到最大数量后中止，请添加计数器
#!/bin/bash
MAX_TRIES="5"
clear
i="$(ifconfig tap0 | awk '{print $2}' | egrep "([0-9]{1,3}[\.]){3}[0-9]{1,3}")"
t="0"
read -p "Enter IP address: " prompt
while [ "$i" != "$prompt" -a "$t" -lt "$MAX_TRIES" ] ; do
echo "Wrong IP address"
t="$((t+1))"
read -p "Enter IP address: " prompt
done
if [ "$t" -eq "$MAX_TRIES" ] ; then
echo "Too many wrong inputs"
exit 1
fi
echo "Correct IP, congrats"
exit 0
评论
0赞
CuriousCase
11/10/2022
检查MAX_TRIES的轻微修改： #！/bin/bash MAX_TRIES=“5” clear i=“$（ifconfig tap0 | awk '{print $2}' | egrep ”（[0-9]{1,3}[\.]）{3}[0-9]{1,3}“）” t=“0” read -p “输入IP地址： ” prompt while [ “$i” ！= “$prompt” -a “$t” -lt “$MAX_TRIES” ] ;do echo “错误的 IP 地址” t=“$（（t+1））” read -p “输入 IP 地址： ” prompt if [ “$t” -eq “$MAX_TRIES” ] ;然后回显“输入错误太多”退出 1 fi 完成回显“正确的 IP，恭喜”退出 0
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