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Full Discussion: Array and Loop Problem
Top Forums Shell Programming and Scripting Array and Loop Problem Post 302441132 by vgersh99 on Thursday 29th of July 2010 10:36:44 AM
Old 07-29-2010
'cat whatever |' creates a subprocess for the 'while read' - the variables within the subprocess/scope stay local and are not accessible outside the subprocess/scope.
 

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IO::Async::Loop::Epoll(3pm)				User Contributed Perl Documentation			       IO::Async::Loop::Epoll(3pm)

NAME
IO::Async::Loop::Epoll - use "IO::Async" with "epoll" on Linux SYNOPSIS
use IO::Async::Loop::Epoll; use IO::Async::Stream; use IO::Async::Signal; my $loop = IO::Async::Loop::Epoll->new(); $loop->add( IO::Async::Stream->new( read_handle => *STDIN, on_read => sub { my ( $self, $buffref ) = @_; while( $$buffref =~ s/^(.*) ? // ) { print "You said: $1 "; } }, ) ); $loop->add( IO::Async::Signal->new( name => 'INT', on_receipt => sub { print "SIGINT, will now quit "; $loop->loop_stop; }, ) ); $loop->loop_forever(); DESCRIPTION
This subclass of IO::Async::Loop uses IO::Epoll to perform read-ready and write-ready tests so that the O(1) high-performance multiplexing of Linux's epoll_pwait(2) syscall can be used. The "epoll" Linux subsystem uses a registration system similar to the higher level IO::Poll object wrapper, meaning that better performance can be achieved in programs using a large number of filehandles. Each epoll_pwait(2) syscall only has an overhead proportional to the number of ready filehandles, rather than the total number being watched. For more detail, see the epoll(7) manpage. This class uses the epoll_pwait(2) system call, which atomically switches the process's signal mask, performs a wait exactly as epoll_wait(2) would, then switches it back. This allows a process to block the signals it cares about, but switch in an empty signal mask during the poll, allowing it to handle file IO and signals concurrently. CONSTRUCTOR
$loop = IO::Async::Loop::Epoll->new() This function returns a new instance of a "IO::Async::Loop::Epoll" object. METHODS
As this is a subclass of IO::Async::Loop, all of its methods are inherited. Expect where noted below, all of the class's methods behave identically to "IO::Async::Loop". $count = $loop->loop_once( $timeout ) This method calls the "poll()" method on the stored "IO::Epoll" object, passing in the value of $timeout, and processes the results of that call. It returns the total number of "IO::Async::Notifier" callbacks invoked, or "undef" if the underlying "epoll_pwait()" method returned an error. If the "epoll_pwait()" was interrupted by a signal, then 0 is returned instead. SEE ALSO
o IO::Epoll - Scalable IO Multiplexing for Linux 2.5.44 and higher o IO::Async::Loop::Poll - use IO::Async with poll(2) AUTHOR
Paul Evans <leonerd@leonerd.org.uk> perl v5.14.2 2012-04-10 IO::Async::Loop::Epoll(3pm)
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