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Fmode(3)	      User Contributed Perl Documentation	      Fmode(3)

       FileHandle::Fmode - determine whether a filehandle is opened for
       reading,	writing, or both.

	use FileHandle::Fmode qw(:all);
	#$fh and FH are	open filehandles
	print is_R($fh), "\n";
	print is_W(\*FH), "\n";

	$bool =	is_FH($fh);
	$bool =	is_FH(\*FH);
	 This is just a	(more intuitively named) alias for is_arg_ok().
	 Returns 1 if its argument is an open filehandle.
	 Returns 0 if its argument is something	other than an open filehandle.

	$bool =	is_arg_ok($fh);
	$bool =	is_arg_ok(\*FH);
	 Returns 1 if its argument is an open filehandle.
	 Returns 0 if its argument is something	other than an open filehandle.

	Arguments to the following functions  must be open filehandles.	If
	any of those functions receive an argument that	is not an open
	filehandle then	the function dies with an appropriate error message.
	To ensure that your script won't suffer	such a death, you could	first
	check by passing the argument to is_FH(). Or you could wrap the
	function call in an eval{} block.

	Note that it may be possible that a filehandle opened for writing may
	become unwritable - if (eg) the	disk becomes full. I don't know	how
	the below functions would be affected by such an event.	I suspect
	that they would	be unaware of the change ... but I haven't actually

	$bool =	is_R($fh);
	$bool =	is_R(\*FH);
	 Returns true if the filehandle	is readable.
	 Else returns false.

	$bool =	is_W($fh);
	$bool =	is_W(\*FH);
	 Returns true if the filehandle	is writable.
	 Else returns false

	$bool =	is_RO($fh);
	$bool =	is_RO(\*FH);
	 Returns true if the filehandle	is readable but	not writable.
	 Else returns false

	$bool =	is_WO($fh);
	$bool =	is_WO(\*FH);
	 Returns true if the filehandle	is writable but	not readable.
	 Else returns false

	$bool =	is_RW($fh);
	$bool =	is_RW(\*FH);
	 Returns true if the filehandle	is both	readable and writable.
	 Else returns false

	$bool =	is_A($fh);
	$bool =	is_A(\*FH);

	 Returns true if the filehandle	was opened for appending.
	 Else returns false.
	 Not currently implemented on Win32 with pre-5.6.1 versions of perl (and
	 dies with appropriate error message if	called on such a platform).

	Inspired (hmmm ... is that the right word ?) by	an idea	from BrowserUK
	posted on PerlMonks in response	to a question from dragonchild.	Win32
	code (including	XS code) provided by BrowserUK.	Zaxo presented the idea
	of using fcntl() in an earlier PerlMonks thread.

	Thanks to dragonchild and BrowserUK for	steering this module in
	the right direction.

	Thanks to attn.steven.kuo for directing	me to the perliol routines
	that enable us to query	filehandles attached to	memory objects.

	And thanks to Jost Krieger for helping to sort out the test failures that
	were occurring on Solaris (and some other operating systems too).

	I don't	know that anyone still runs pre-5.6.1 perl on Win32. However, if
	someone	likes to tell me how is_A() could be made to work on pre-5.6.1
	Win32 perl, I would be quite happy to implement	it.

	This program is	free software; you may redistribute it and/or
	modify it under	the same terms as Perl itself.
	Copyright 2006-2008, 2009, 2010, 2012 Sisyphus

	Sisyphus <sisyphus at cpan dot org>

perl v5.32.0			  2014-08-09			      Fmode(3)


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