Example 14-2. db2gdbm

  #!/usr/bin/perl -w
  # db2gdbm: converts DB to GDBM
  
  use strict;
  
  use DB_File;
  use GDBM_File;
  
  unless (@ARGV =  = 2) {
      die "usage: db2gdbm infile outfile\n";
  }
  
  my ($infile, $outfile) = @ARGV;                     
  my (%db_in, %db_out);                               
  
  # open the files
  tie(%db_in, 'DB_File', $infile)
      or die "Can't tie $infile: $!";
  tie(%db_out, 'GDBM_File', $outfile, GDBM_WRCREAT, 0666)
      or die "Can't tie $outfile: $!";
  
  # copy (don't use %db_out = %db_in because it's slow on big databases)
  while (my($k, $v) = each %db_in) {
      $db_out{$k} = $v;
  }
  
  # these unties happen automatically at program exit
  untie %db_in;
  untie %db_out;