Will it work theoretically?Say, will the thread be able to capture q if it's already consumed by more?

Theoretically yes,I think your only way to do it that way is to somehow dup stdin. See 

Found in /usr/lib/perl5/5.14.1/pod/perlfaq5.pod
   How do I dup() a filehandle in Perl?
   If you check "open" in perlfunc, you'll see that several of the way
+s to
       call open() should do the trick. For example:

               open my $log, '>>', '/foo/logfile';
               open STDERR, '>&LOG';

       Or even with a literal numeric descriptor:

               my $fd = $ENV{MHCONTEXTFD};
               open $mhcontext, "<&=$fd";  # like fdopen(3S)

       Note that "<&STDIN" makes a copy, but "<&=STDIN" makes an alias
+. That
       means if you close an aliased handle, all aliases become inacce
+ssible.
       This is not true with a copied one.

       Error checking, as always, has been left as an exercise for the
+ reader.

[download]
Then your stdin watcher thread and main thread might be able to both get the q . As with error checking, seeing if it works is left as an exercise to the OP. :-). Googling for "perl duping stdin" should give you some already written code.

But I think you are trying to do this the hard way, you probably would be better off putting your code into an eventloop of some sort, and using a piped open to run your $cmd.

I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku ................... flash japh

In reply to Re^3: How to know whether user terminates system("$cmd|more") with q or not? by zentara
in thread How to know whether user terminates system("$cmd|more") with q or not? by PerlOnTheWay

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