There's two ways I can think of to do it - one is via threading your perl, to make your 'reading STDIN' run in parallel. Something like:
#!/usr/bin/perl use strict; use warnings; use threads; use Thread::Queue; my $input_q = Thread::Queue -> new(); sub stdin_reader { while ( my $line = <STDIN> ) { if ( defined $input_q -> pending() ) { $input_q -> enqueue ( $line ); } else { last; } } } sub doing_stuff_thread { my $count = 0; while ( $count < 10 ) { my $item = $input_q -> dequeue_nb(); if ( defined $item ) { print "Got: $item"; $count++; } else { print "Doing something else, because nothing on STDIN\n"; print "Pending items:", $input_q -> pending(), "\n"; sleep 1; } } $input_q -> end(); } threads -> create ( \&stdin_reader ); threads -> create ( \&doing_stuff_thread ); foreach my $thr ( threads -> list() ) { print "Waiting for ",$thr -> tid()," to join\n"; $thr -> join(); }
That works, although bear in mind that 'STDIN' is being read line by line, so you need to put carriage returns in. (you can't do 'readkey' style). (And also - you may find 'Thread::Queue' isn't 'standard', but I'm sure you can figure out how to do something useful with thread::shared and lock instead.
The other way I can think of involves using IO::Select. Or perhaps like this node: Here
#!/usr/bin/perl use strict; use warnings; use IO::Handle; use IO::Select; my $nb_stdin = new IO::Select( *STDIN ); while ( 1 ) { if ( $nb_stdin -> can_read(0) ) { my $line = <STDIN>; print "Got: ", $line,"\n"; } else { print "Nothing on STDIN, doing something else\n"; sleep 1; } }
This doesn't seem to work properly on Win32/Activestate though - I believe I've seen something to the effect that IO::Select doesn't work on non-sockets on W32. YMMV
In reply to Re: Checing presence of input on standard input in non-blocking way, sans user interaction
by Preceptor
in thread Checing presence of input on standard input in non-blocking way, sans user interaction
by Anonymous Monk
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