Shell 如果没有用户的回复，则执行命令

我正在写一个剧本，必须等一段时间。如果用户在这段时间内没有得到回复，脚本必须退出

乙二醇

如果用户在30秒内没有回复[是或否]，则必须转到else分支

我们怎么做

我试着这样做：

read choice || sleep 30

使用带-t超时键的读取

-t timeout
                 Cause  read  to time out and return failure if a complete
                 line of input is not read within timeout seconds.   time‐
                 out  may  be  a  decimal number with a fractional portion
                 following the decimal point.  This option is only  effec‐
                 tive  if  read is reading input from a terminal, pipe, or
                 other special file; it has no effect  when  reading  from
                 regular  files.  If timeout is 0, read returns success if
                 input is available  on  the  specified  file  descriptor,
                 failure  otherwise.   The exit status is greater than 128
                 if the timeout is exceeded.

因此，在你的情况下：

read -t 30 answer
[ "$?" > 128 ] && TIMEOUT=YES
if [ "$answer" = yes ]
then
   echo User replied yes
else
   if [ "$TIMEOUT" = YES ]
   then
     echo User did not reply
   else
     echo User replied something other
   fi
fi

---

读输入然后请考虑。@ Igor Chubin，你的脚本在最后一个部分中不能正常工作。阅读后，如果答案不是“是”，那么最后一个else部分将执行，但执行第二个else部分，因此我在文章中做了一些更改。

read -t 30 answer
[ "$?" > 128 ] && TIMEOUT=YES
if [ "$answer" = yes ]
then
   echo User replied yes
else
   if [ "$TIMEOUT" = YES ]
   then
     echo User did not reply
   else
     echo User replied something other
   fi
fi