Substitue for read -t ?

linj · 09-23-2004, 08:08 AM

I am running bash version 1.14.7(1) and I need to write a script to ask for user input from the console and wait x seconds and if there is no response in x seconds continue on. read –t would be great but this does not work in this version of bash and upgrading at this point is not an option. Can anyone tell me if there is another way to do this besides read –t?

Thanks!

jim mcnamara · 09-23-2004, 02:27 PM

Korn shell should be on your box.

Try ksh coprocesses:

asynchronous signal:

Code:

#!/bin/ksh
# file: asynch_signal.shl
sleep $1
kill -USR2 $PPID
exit

main script:

Code:

#!/bin/ksh
input=""
readit()
{
trap "return" USR2
asynch_signal.shl 10 |&
read input        
trap "" USR2 
echo "got here"
exit
}

echo "starting to read"
readit
echo "input = $input"

exit

cracauer · 09-23-2004, 02:55 PM

The only portable way to do that is to fork and have one brnach read and the other one kill the reading one after a sleep.

jim mcnamara · 09-23-2004, 03:19 PM

I think he wants a shell script method.

Your C or whatever program method is the best answer.

linj · 09-23-2004, 08:59 PM

Jim
I tried your code and am getting:

syntax error near unexpected token '&'
line 7: 'asynch_signal.shl 10 |&'

Yes I would like a shell script method if possible but I can do c++. However, I am a linux rookie and have not tried any c++ for linux yet but I am willing to try. What is the recommened compiler for linux?

Thanks a lot for the posts guys!

cracauer · 09-23-2004, 09:23 PM

Of course you can fork from the shellscript.

Too lazzy to do a real one but here's the basics:

#! /bin/sh
otherpid=$$
(
sleep 10
kill $otherpid
# take over from other script
)
otherpid=$!
read foo
kill $otherpid