1Fmode(3)              User Contributed Perl Documentation             Fmode(3)
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NAME

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

10        use FileHandle::Fmode qw(:all);
11        .
12        .
13        #$fh and FH are open filehandles
14        print is_R($fh), "\n";
15        print is_W(\*FH), "\n";
16

FUNCTIONS

18        $bool = is_arg_ok($fh);
19        $bool = is_arg_ok(\*FH);
20         Returns 1 if its argument is an open filehandle.
21         Returns 0 if its argument is something other than an open filehandle.
22
23        Arguments to the following functions  must be open filehandles. If
24        any of those functions receive an argument that is not an open
25        filehandle then the function dies with an appropriate error message.
26        To ensure that your script won't suffer such a death, you could first
27        check by passing the argument to is_arg_ok(). Or you could wrap the
28        function call in an eval{} block.
29
30        $bool = is_R($fh);
31        $bool = is_R(\*FH);
32         Returns true if the filehandle is readable.
33         Else returns false.
34
35        $bool = is_W($fh);
36        $bool = is_W(\*FH);
37         Returns true if the filehandle is writable.
38         Else returns false
39
40        $bool = is_RO($fh);
41        $bool = is_RO(\*FH);
42         Returns true if the filehandle is readable but not writable.
43         Else returns false
44
45        $bool = is_WO($fh);
46        $bool = is_WO(\*FH);
47         Returns true if the filehandle is writable but not readable.
48         Else returns false
49
50        $bool = is_RW($fh);
51        $bool = is_RW(\*FH);
52         Returns true if the filehandle is both readable and writable.
53         Else returns false
54
55        $bool = is_A($fh);
56        $bool = is_A(\*FH);
57
58         Returns true if the filehandle was opened for appending.
59         Else returns false.
60         Not currently implemented on Win32 with pre-5.6.1 versions of perl (and
61         dies with appropriate error message if called on such a platform).
62

CREDITS

64        Inspired (hmmm ... is that the right word ?) by an idea from BrowserUK
65        posted on PerlMonks in response to a question from dragonchild. Win32
66        code (including XS code) provided by BrowserUK. Zaxo presented the idea
67        of using fcntl() in an earlier PerlMonks thread.
68
69        Thanks to dragonchild and BrowserUK for steering this module in
70        the right direction.
71
72        Thanks to attn.steven.kuo for directing me to the perliol routines
73        that enable us to query filehandles attached to memory objects.
74
75        And thanks to Jost Krieger for helping to sort out the test failures that
76        were occurring on Solaris (and some other operating systems too).
77

TODO

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

84        This program is free software; you may redistribute it and/or
85        modify it under the same terms as Perl itself.
86

AUTHOR

88        Sisyphus <kalinabears at iinet dot net dot au>
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92perl v5.12.0                      2006-05-12                          Fmode(3)