IO::Tee - Multiplex output to multiple output handles
use IO::Tee;
$tee = IO::Tee->new($handle1, $handle2);
print $tee "foo", "bar";
my $input = <$tee>;
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.
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);
https://github.com/neilb/IO-Tee
Chung-chieh Shan, ken@digitas.harvard.edu
As of August 2017, now being maintained by Neil Bowers.
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.
perlfunc, the IO::Handle manpage, the IO::File manpage.
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