how to check for keyboard input

redss has asked for the wisdom of the Perl Monks concerning the following question:

Hello monks!

My program needs to process data and periodically poll for keyboard input.
What function can I use on the third line to check if a key was pressed, without waiting forever for input?

while (1) {
  sleep(1);

  if key was pressed {   # HELP, how can I check?
    print "$key was pressed\n";
    exit if $key eq 'q';
  }

  do stuff...
}
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Comment on how to check for keyboard input Download Code

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Re: how to check for keyboard input by Tanktalus (Canon) on Jul 21, 2005 at 04:14 UTC
Check out Term::ReadKey. Its synopsis almost exactly shows what you want.	[reply]
Re: how to check for keyboard input by tlm (Prior) on Jul 21, 2005 at 04:15 UTC
`use strict; use warnings; use Term::ReadKey; my $done; while ( 1 ) { sleep 1; ReadMode( 'cbreak' ); if ( defined ( my $key = ReadKey( -1 ) ) ) { # input waiting; it's in $key $done = $key eq 'q'; } ReadMode( 'normal' ); exit if $done; # do stuff... }` [download] Update: Thanks to Tanktalus for pointing out the exit bug. Also thanks to bobf for pointing out typo in comment. Both fixed. the lowliest monk	[reply] [d/l]
Re^2: how to check for keyboard input by Tanktalus (Canon) on Jul 21, 2005 at 04:17 UTC
Warning: you need to set the readmode back to normal before exiting. So don't just exit on 'q' - do something to get the terminal back into its regular state. `sub safe_exit { ReadMode('normal'); exit(@_); } # ... safe_exit if $key eq 'q'; # ...` [download]	[reply] [d/l]
Re^3: how to check for keyboard input by chb (Deacon) on Jul 21, 2005 at 08:07 UTC
To be extra sure the terminal is in a sane state after the program exits, the `safe_exit` routine could be hooked in some other places, too, e.g. `$SIG{'INT'} = \&safe_exit; $SIG{'QUIT'} = \&safe_exit; $SIG{__DIE__} = \&safe_exit; END { safe_exit(); }` [download] --- Update: oops, references added, as benizi pointed out below	[reply] [d/l] [select]
Re: how to check for keyboard input by benizi (Hermit) on Jul 21, 2005 at 17:17 UTC


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