NAME

       IO::Tee - Multiplex output to multiple output handles

SYNOPSIS

           use IO::Tee;

           $tee = IO::Tee->new($handle1, $handle2);
           print $tee "foo", "bar";
           my $input = <$tee>;

DESCRIPTION

       "IO::Tee" objects can be used to multiplex input and output in two different ways.  The
       first way is to multiplex output to zero or more output handles.  The "IO::Tee"
       constructor, given a list of output handles, returns a tied handle that can be written to.
       When written to (using print or printf), the "IO::Tee" object multiplexes the output to
       the list of handles originally passed to the constructor.  As a shortcut, you can also
       directly pass a string or an array reference to the constructor, in which case
       "IO::File::new" is called for you with the specified argument or arguments.

       The second way is to multiplex input from one input handle to zero or more output handles
       as it is being read.  The "IO::Tee" constructor, given an input handle followed by a list
       of output handles, returns a tied handle that can be read from as well as written to.
       When written to, the "IO::Tee" object multiplexes the output to all handles passed to the
       constructor, as described in the previous paragraph.  When read from, the "IO::Tee" object
       reads from the input handle given as the first argument to the "IO::Tee" constructor, then
       writes any data read to the output handles given as the remaining arguments to the
       constructor.

       The "IO::Tee" class supports certain "IO::Handle" and "IO::File" methods related to input
       and output.  In particular, the following methods will iterate themselves over all handles
       associated with the "IO::Tee" object, and return TRUE indicating success if and only if
       all associated handles returned TRUE indicating success:

       close
       truncate
       write
       syswrite
       format_write
       formline
       fcntl
       ioctl
       flush
       clearerr
       seek

       The following methods perform input multiplexing as described above:

       read
       sysread
       readline
       getc
       gets
       eof
       getline
       getlines

       The following methods can be used to set (but not retrieve) the current values of output-
       related state variables on all associated handles:

       autoflush
       output_field_separator
       output_record_separator
       format_page_number
       format_lines_per_page
       format_lines_left
       format_name
       format_top_name
       format_line_break_characters
       format_formfeed

       The following methods are directly passed on to the input handle given as the first
       argument to the "IO::Tee" constructor:

       input_record_separator
       input_line_number

       Note that the return value of input multiplexing methods (such as "print") is always the
       return value of the input action, not the return value of subsequent output actions.  In
       particular, no error is indicated by the return value if the input action itself succeeds
       but subsequent output multiplexing fails.

EXAMPLE

           use IO::Tee;
           use IO::File;

           my $tee = new IO::Tee(\*STDOUT,
               new IO::File(">tt1.out"), ">tt2.out");

           print join(' ', $tee->handles), "\n";

           for (1..10) { print $tee $_, "\n" }
           for (1..10) { $tee->print($_, "\n") }
           $tee->flush;

           $tee = new IO::Tee('</etc/passwd', \*STDOUT);
           my @lines = <$tee>;
           print scalar(@lines);

REPOSITORY

       <https://github.com/neilb/IO-Tee>

AUTHOR

       Chung-chieh Shan, ken@digitas.harvard.edu

       As of August 2017, now being maintained by Neil Bowers.

COPYRIGHT

       Copyright (c) 1998-2017 Chung-chieh Shan.  All rights reserved.  This program is free
       software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

       perlfunc, IO::Handle, IO::File.