PerlIO::tee - Multiplex output layer
open my $out, '>>:tee', $file, @sources; $out->push_layer(tee => $file); $out->push_layer(tee => ">> $file"); $out->push_layer(tee => \$scalar); $out->push_layer(tee => \*FILEHANDLE);
PerlIO::tee provides a multiplex output stream like tee(1). It makes a filehandle write to one or more files (or scalars via the :scalar layer) at the same time.
PerlIO::tee
tee(1)
:scalar
You can use push_layer() (defined in PerlIO::Util) to add a source to a filehandle. The source may be a file name, a scalar reference, or a filehandle. For example:
push_layer()
PerlIO::Util
$fh->push_layer(tee => $file); # meaning "> $file" $fh->push_layer(tee => ">>$file");# append mode $fh->push_layer(tee => \$scalar); # via :scalar $fh->push_layer(tee => \*OUT); # shallow copy, not duplication
You can also use open() with multiple arguments. However, it is just a syntax sugar to call push_layer(): One :tee layer has a single extra output stream, so arguments $x, $y, $z of open(), for example, prepares a filehandle with one default layer and two :tee layers with a internal output stream.
open()
:tee
$x, $y, $z
open my $tee, '>:tee', $x, $y, $z; # the code above means: # open my $tee, '>', $x; # $tee->push_layer(tee => $y); # $tee->push_layer(tee => $z); $tee->get_layers(); # => "perlio", "tee($y)", "tee($z)" $tee->pop_layer(); # "tee($z)" is popped $tee->pop_layer(); # "tee($y)" is popped # now $tee is a filehandle only to $x
Here is a minimal implementation of tee(1).
#!/usr/bin/perl -w # Usage: $0 files... use strict; use PerlIO::Util; *STDOUT->push_layer(tee => $_) for @ARGV; while(read STDIN, $_, 2**12){ print; } __END__
PerlIO::Util.
Goro Fuji (藤 吾郎) <gfuji (at) cpan.org>
Copyright (c) 2008, Goro Fuji <gfuji (at) cpan.org>. Some rights reserved.
This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
To install PerlIO::Util, copy and paste the appropriate command in to your terminal.
cpanm
cpanm PerlIO::Util
CPAN shell
perl -MCPAN -e shell install PerlIO::Util
For more information on module installation, please visit the detailed CPAN module installation guide.