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);
AUTHOR¶
Chung-chieh Shan, ken@digitas.harvard.edu
COPYRIGHT¶
Copyright (c) 1998-2001 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.