user input timeouts?

[kclark at CetaceanNetworks.com (Kevin D. Clark)]

Bob Keyes writes:

> On 10 Feb 2004, Kevin D. Clark wrote:
> > Obviously, there are more complicated ways to do this as well.
> 
> Hrm...

Something like this comes to mind:

    #!/bin/sh
    # ash?
    
    # pass this two arguments:
    # first argument: default value if timeout occurs
    # second argument: timeout
    timed_read() {
      trap "echo TIMEOUT ; timed_read_result=$1; return" USR1
      child=`sh -c "(sleep $2; kill -USR1 $$) 1>&- 2>&- & echo \\$\\$"`
      read timed_read_result
      kill $child 1>&- 2>&-
      return
    }
    
    echo -n "Initiate self-destruct sequence? "
    timed_read n 2
    
    echo timed_read_result is $timed_read_result
    exit 0

Note: this is a quick hack.  It needs polishing.  Since I don't work
with ash too often, it seems prudent to let you do the polishing.

Hope this helps,

--kevin
-- 
Kevin D. Clark / Cetacean Networks / Portsmouth, N.H. (USA)
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