Re: DBM file corruption?

To start, if the data is text, dump the dbm to a text file and see if keys and data are what you expect, see if they are reasonable.

YuckFoo


#!/usr/bin/perl

   use strict;

   if (@ARGV < 1) {
      print STDERR "\nUsage $0 dbfile\n\n"; exit;
   }

   my ($dbfile) = @ARGV;
   my (%DB, $key, $val);

   if (!dbmopen(%DB, $dbfile, 0444) ) {
      print STDERR "\nError opening file $dbfile\n\n"; exit;
   }

   while ( ($key, $val) = each %DB) {
      print "$key,$val\n";
   }

   dbmclose(%DB);
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Re (tilly) 2: DBM file corruption? by tilly (Archbishop) on Jan 15, 2002 at 09:19 UTC
Two issues. The obvious one is that often knowing what the exact error is and what line it is on is often very important. So you should use die, without a return in it, and have $! in the die statement. (Just like it says in perlstyle.) The second, more subtle, issue is that dbmopen is unsafe. It will assume that your dbm files are stored in the "best" format that your Perl knows how to handle. As files move from machine to machine, or if you install a new module, the "best" format may change, meaning that your code no longer knows how to read the dbm file from disk. It is therefore far better IMNSHO to use tie and be explicit about how you are accessing the dbm file.	[reply]

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Re (tilly) 2: DBM file corruption?
by tilly (Archbishop) on Jan 15, 2002 at 09:19 UTC

The obvious one is that often knowing what the exact error is and what line it is on is often very important. So you should use die, without a return in it, and have $! in the die statement. (Just like it says in perlstyle.)

The second, more subtle, issue is that dbmopen is unsafe. It will assume that your dbm files are stored in the "best" format that your Perl knows how to handle. As files move from machine to machine, or if you install a new module, the "best" format may change, meaning that your code no longer knows how to read the dbm file from disk. It is therefore far better IMNSHO to use tie and be explicit about how you are accessing the dbm file.

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