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DB_File - flock

Posted on 1998-11-01
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Last Modified: 2010-03-04
This is an attempt to flock a database, a modified version of a snippet of code from the PERL docs at http://www.perl.com/CPAN-local/doc/manual/html/lib/DB_File.html#HINTS_AND_TIPS.

# begin code

use DB_File;
use Fcntl;
# ...
$database = "/home/test/temp.dbm";
$db = tie(%hash, DB_File, $database, O_RDRW|O_CREAT, 0777) || die "Could not tie database!";
$fd = $db->fd;
open(DB_FH, "+<&=$fd") || die "dup ($!)";  # dies here
flock (DB_FH, 1);
# ...
flock (DB_FH, 8);
undef $db;
untie(%hash);
close(DB_FH);

# end code

The error arises from the line: open(DB_FH, "+<&=$fd").  Now, I understand  the concept behind "+<&$fd", but why would this open fail when the tie() did not?  The script terminates without setting $!.

If anyone can answer this I would really appreciate it.  Pardon any typos, its been a long weekend.

Daniel Crowe
Evernight Design
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Question by:Evernight
  • 4
5 Comments
 

Author Comment

by:Evernight
ID: 1205859
Adjusted points to 150
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Author Comment

by:Evernight
ID: 1205860
I don't think I've ever spent so much time trying to figure out what the leters "dup" stand for. ;p
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Author Comment

by:Evernight
ID: 1205861
Anyone have any idea?  Even a hint or suggestion?  Please.
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Author Comment

by:Evernight
ID: 1205862
Adjusted points to 209
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Accepted Solution

by:
Igloo earned 200 total points
ID: 1205863
Try RDWR intead of RDRW ;-)
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