如何使用 Bash 读取超时？
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How to use Bash read with a timeout?
提问by qdii
I can ask the user to press Enterby 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:
我可以要求用户按Enter使用read，并通过调用让他等待sleep。但我想不出同时做这两件事的方法。我希望用户有以下选择：
Press Ctrl+Cto Cancel, Enter?to continue or just wait 10?seconds
按Ctrl+C取消，按Enter? 继续或等待 10? 秒
How can I?do that?
我怎样才能做到这一点？
回答by paxdiablo
In bash, readhas a -toption where you can specify a timeout. From the manpage:
在bash,read有一个-t选项，您可以在其中指定超时。从联机帮助页：
read [-ers] [-u fd] [-t timeout] [-a aname] [-p prompt] [-n nchars] [-d delim] [name ...]
-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.
read [-ers] [-u fd] [-t timeout] [-a aname] [-p prompt] [-n nchars] [-d delim] [name ...]
-t timeout:如果在超时秒内未读取完整的输入行，则会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。
Transcript below (without hitting ENTER):
下面的成绩单（不按回车键）：
$ 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
Another, hitting ENTER after a couple of seconds:
另一个，几秒钟后按 ENTER 键：
$ 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
And another, hitting CTRL-C:
另一个，按 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
回答by Johannes Weiss
The readbuiltin has a timeout.
该read内置有超时。
read -t 10
will do it
会做的
回答by Benoit
From the bash reference manual:
read [-ers] [-a aname] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt][-t timeout][-u fd] [name ...]
read [-ers] [-a aname] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt][-t timeout][-u fd] [name ...]
