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

问题描述

我可以使用read让用户按Enter，然后通过调用sleep让他等待.但我想不出同时做这两件事的方法.我希望用户有选择权:

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，Enter 继续或等待 10 秒

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

我该怎么做?

推荐答案

在 bash 中，read 有一个 -t 选项，你可以指定超时.来自联机帮助页:

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: 如果在 timeout 秒内没有读取完整的输入行，则导致读取超时并返回失败.如果 read 不是从终端或管道读取输入，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(不按回车键):

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

另一个，按 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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