shell_50.Linux获取用户输入_超时

微辣已是极限2023-10-26 11:24

超时

使用 read 命令时要当心。脚本可能会一直苦等着用户输入。如果不管是否有数据输入，脚

本都必须继续执行，你可以用-t 选项来指定一个计时器。-t 选项会指定 read 命令等待输入的

秒数。如果计时器超时，则 read 命令会返回非 0 退出状态码：

$ cat asknametimed.sh 
#!/bin/bash 
# Using the read command with a timer 
# 
if read -t 5 -p "Enter your name: " name 
then 
    echo "Hello $name, welcome to my script." 
else 
    echo 
    echo "Sorry, no longer waiting for name." 
fi 
exit 
$ 
$ ./asknametimed.sh 
Enter your name: Christine 
Hello Christine, welcome to my script. 
$ 
$ ./asknametimed.sh 
Enter your name: 
Sorry, no longer waiting for name. 
$

可以不对输入过程计时，而是让 read 命令统计输入的字符数。当字符数达到预设值时，

就自动退出，将已输入的数据赋给变量：

$ cat continueornot.sh 
#!/bin/bash 
# Using the read command for one character 
# 
read -n 1 -p "Do you want to continue [Y/N]? " answer 
# 
case $answer in 
    Y | y) echo 
        echo "Okay. Continue on...";; 
    N | n) echo 
    echo "Okay. Goodbye" 
    exit;; 
esac 
echo "This is the end of the script." 
exit 
$ 
$ ./continueornot.sh

Do you want to continue [Y/N]? Y
Okay. Continue on... 
This is the end of the script. 
$ 
$ ./continueornot.sh 
Do you want to continue [Y/N]? n
Okay. Goodbye 
$