IO::Tee(3)            User Contributed Perl Documentation           IO::Tee(3)


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.

perl v5.38.0                      2023-07-26                        IO::Tee(3)