如何使用Bash读取超时? [英] How to use Bash read with a timeout?

问题描述

我可以要求用户使用read按下 Enter ，然后通过调用sleep让他等待.但是我想不出同时做这两种方式的方法.我希望为用户提供选择:

I can ask the user to press Enter by using read, and have him wait by calling sleep. But I can’t think of a way of doing both at the same time. I would like the user to be given the choice:

按 Ctrl + C 取消，按 Enter 继续或仅等待10秒

Press Ctrl+C to Cancel, Enter to continue or just wait 10 seconds

我该怎么办?

推荐答案

在bash中，read具有-t选项，您可以在其中指定超时.在联机帮助页上:

In bash, read has a -t option where you can specify a timeout. From the manpage:

read [-ers] [-u fd] [-t timeout] [-a aname] [-p prompt] [-n nchars] [-d delim] [name ...]

-t timeout: 导致读取超时，如果在超时秒内未读取完整的输入行，则返回失败.如果读取未读取来自终端或管道的输入，则此选项无效.

-t timeout: cause read to time out and return failure if a complete line of input is not read within timeout seconds. This option has no effect if read is not reading input from the terminal or a pipe.

下面的成绩单(不按ENTER):

Transcript below (without hitting ENTER):

$ date ; read -t 10 -p "Hit ENTER or wait ten seconds" ; echo ; date
Tue Feb 28 22:29:15 WAST 2012
Hit ENTER or wait ten seconds
Tue Feb 28 22:29:25 WAST 2012

另一个，几秒钟后按ENTER键:

Another, hitting ENTER after a couple of seconds:

$ date ; read -t 10 -p "Hit ENTER or wait ten seconds" ; date
Tue Feb 28 22:30:17 WAST 2012
Hit ENTER or wait ten seconds
Tue Feb 28 22:30:19 WAST 2012

然后按下CTRL-C:

And another, hitting CTRL-C:

$ date ; read -t 10 -p "Hit ENTER or wait ten seconds" ; echo ; date
Tue Feb 28 22:30:29 WAST 2012
Hit ENTER or wait ten seconds

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