use IO::Handle;
    $fh = new IO::Handle;
    if ($fh->fdopen(fileno(STDIN),"r")) {
        print $fh->getline;
        $fh->close;
    }
    $fh = new IO::Handle;
    if ($fh->fdopen(fileno(STDOUT),"w")) {
        $fh->print("Some text\n");
    }
    use IO::Handle '_IOLBF';
    $fh->setvbuf($buffer_var, _IOLBF, 1024);
undef $fh; # automatically closes the file if it's open
autoflush STDOUT 1;
IO::Handle is the base class for all other 
IO handle classes. It is not intended that objects of IO::Handle would be created directly, but instead IO::Handle is inherited from by several other classes in the 
IO hierarchy.
If you are reading this documentation, looking for a replacement for the FileHandle package, then 
I suggest you read the documentation for IO::File
A IO::Handle object is a reference to a symbol (see the Symbol package)
IO::Handle object.
IO::Handle like new does. It requires two parameters, which are passed to the method fdopen; if the fdopen fails, the object is destroyed. Otherwise, it is returned
to the caller.
IO::Handle methods, which are just front ends for the corresponding built-in
functions:
    close
    fileno
    getc
    eof
    read
    truncate
    stat
    print
    printf
    sysread
    syswrite
See the perlvar manpage for complete descriptions of each of the following supported IO::Handle methods:
    autoflush
    output_field_separator
    output_record_separator
    input_record_separator
    input_line_number
    format_page_number
    format_lines_per_page
    format_lines_left
    format_name
    format_top_name
    format_line_break_characters
    format_formfeed
    format_write
Furthermore, for doing normal I/O you might need these:
fdopen is like an ordinary open except that its first parameter is not a filename but rather a file handle
name, a IO::Handle object, or a file descriptor number.
croak() if accidentally called in a scalar context.
format_write.
clearerr.
setbuf() and/or
setvbuf() are available, then
IO::Handle::setbuf and IO::Handle::setvbuf set the buffering policy for an IO::Handle. The calling sequences for the Perl functions are the same as their 
C counterparts--including the constants
 _IOFBF,
_IOLBF, and _IONBF for setvbuf()--except that the buffer parameter specifies a scalar variable to use as a buffer. 
WARNING: 
A variable used as a buffer by
 setbuf or setvbuf must not be modified in any way until the IO::Handle is closed or setbuf or setvbuf is called again, or memory corruption may result! Note that you need to
import the constants _IOFBF, _IOLBF, and _IONBF explicitly.
Lastly, there is a special method for working under -T and setuid/gid scripts:
IO::Handle object is a 
GLOB reference. Some modules that inherit from IO::Handle may want to keep object related variables in the hash table part of the 
GLOB. In an attempt to prevent modules trampling on each other 
I propose the that any such module should prefix its variables with its own name separated by _'s. For example the IO::Socket module keeps a
 timeout variable in 'io_socket_timeout'.
IO::Handle, or actually classes derived from that class. They actually aren't. Which
means you can't derive your own class from IO::Handle and inherit those methods.