stat or, more conveniently, the -w file test operator. Both work fine on open handles, though we're mostly used to feeding them file names.

Update: Oops, got the wrong end of the stick. Here's how to check the open flags to see if the handle is currently writable: 

use Fcntl;

sub writable {
    my $fh = shift;
    (O_WRONLY | O_RDWR) & fcntl( $fh, F_GETFL, my $slush);
}

for (qw/ > < >> +< +> /) {
    open my $fh, $_, 'foo' or warn $! and next;
    print
        "$_\t",
        writable($fh)? 'writable.': 'not writable.',
        $/;
}

__END__
>       writable.
<       not writable.
>>      writable.
+<      writable.
+>      writable.

[download]

After Compline,
Zaxo

In reply to Re: How do I tell if a handle is open for writing? by Zaxo
in thread How do I tell if a handle is open for writing? by DrWhy

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