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    $outfh->autoflush(1) if UNIVERSAL::can($outfh, 'autoflush');
    $errfh->autoflush(1) if UNIVERSAL::can($errfh, 'autoflush');

    while (my @ready = $sel->can_read) {
        foreach my $fh (@ready) { # loop through buffered handles
            # read up to 4096 bytes from this fh.
            my $len = sysread $fh, my($buf), 4096;

            if (not defined $len){
                # There was an error reading
                warn loc("Error from child: %1",$!);
                return(undef, $!);
            }
            elsif ($len == 0){
                $sel->remove($fh); # finished reading
                next;
            }
            elsif ($fh == $outfh) {
                $_out_handler->($buf);
            } elsif ($fh == $errfh) {
                $_err_handler->($buf);
            } else {
                warn loc("%1 error", 'IO::Select');
                return(undef, $!);
            }
        }
    }

    waitpid $pid, 0; # wait for it to die
    return 1;
}

1;

__END__

=pod

=head1 NAME

IPC::Cmd - finding and running system commands made easy

=head1 SYNOPSIS

    use IPC::Cmd qw[can_run run];

    my $full_path = can_run('wget') or warn 'wget is not installed!';


    ### commands can be arrayrefs or strings ###
    my $cmd = "$full_path -b theregister.co.uk";
    my $cmd = [$full_path, '-b', 'theregister.co.uk'];

    ### in scalar context ###
    if( run(command => $cmd, verbose => 0) ) {
        print "fetched webpage succesfully\n";
    }


    ### in list context ###
    my( $succes, $error_code, $full_buf, $stdout_buf, $stderr_buf ) =
            run( command => $cmd, verbose => 0 );

    if( $success ) {
        print "this is what the command printed:\n";
        print join "", @$full_buf;
    }


    ### don't have IPC::Cmd be verbose, ie don't print to stdout or
    ### stderr when running commands -- default is '0'
    $IPC::Cmd::VERBOSE = 0;

=head1 DESCRIPTION

IPC::Cmd allows you to run commands, interactively if desisered,
platform independant but have them still work.

The C<can_run> function can tell you if a certain binary is installed
and if so where, whereas the C<run> function can actually execute any
of the commands you give it and give you a clear return value, as well
as adhere to your verbosity settings.

=head1 FUNCTIONS

=head2 can_run

C<can_run> takes but a single argument: the name of a binary you wish
to locate. C<can_run> works much like the unix binary C<which>, which
scans through your path, looking for the binary you asked for.

Unlike C<which> however, this function is platform independant and
will also work on, for example, Win32.

It will return the full path to the binary you asked for if it was
found, or C<undef> if it was not.

=head2 run

C<run> takes 2 arguments:

=over 4

=item command

This is the command to execute. It may be either a string or an array
reference.
This is a required argument.

=item verbose

This controls whether all output of a command should also be printed
to STDOUT/STDERR or should only be trapped in buffers (NOTE: buffers
require C<IPC::Run> to be installed or your system able to work with
C<IPC::Open3>).

It will default to the global setting of C<$IPC::Cmd::VERBOSE>,
which by default is 0.

=back

C<run> will return a simple C<true> or C<false> when called in scalar
context.
In list context, you will be returned a list of the following items:

=over 4

=item success

A simple boolean indicating if the command executed without errors or
not.