How to use Bash read with a timeout?

In bash⁽¹⁾, 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: 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.

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

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

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

⁽¹⁾ If you’re doing this in a script, make sure that it’s a bash one. You can do that by adding a shebang line at the start such as one of the following:

#!/usr/bin/env bash
#!/bin/bash