was documented in #6417.
p4raw-id: //depot/perl@6701
=head1 SYNOPSIS
- use NDBM_File;
- use Fcntl; # for O_ constants
+ use Fcntl; # For O_RDWR, O_CREAT, etc.
+ use NDBM_File;
- tie(%h, 'NDBM_File', 'Op.dbmx', O_RDWR|O_CREAT, 0640);
+ # Now read and change the hash
+ $h{newkey} = newvalue;
+ print $h{oldkey};
+ ...
+
+ untie %h;
+
+=head1 DESCRIPTION
+
+C<NDBM_File> establishes a connection between a Perl hash variable and
+a file in NDBM_File format;. You can manipulate the data in the file
+just as if it were in a Perl hash, but when your program exits, the
+data will remain in the file, to be used the next time your program
+runs.
- untie %h;
+Use C<NDBM_File> with the Perl built-in C<tie> function to establish
+the connection between the variable and the file. The arguments to
+C<tie> should be:
-=head1 DESCRIPTION
+=over 4
+
+=item 1.
+
+The hash variable you want to tie.
+
+=item 2.
+
+The string C<"NDBM_File">. (Ths tells Perl to use the C<NDBM_File>
+package to perform the functions of the hash.)
+
+=item 3.
+
+The name of the file you want to tie to the hash.
+
+=item 4.
+
+Flags. Use one of:
+
+=over 2
+
+=item C<O_RDONLY>
+
+Read-only access to the data in the file.
+
+=item C<O_WRONLY>
+
+Write-only access to the data in the file.
+
+=item C<O_RDWR>
+
+Both read and write access.
+
+=back
+
+If you want to create the file if it does not exist, add C<O_CREAT> to
+any of these, as in the example. If you omit C<O_CREAT> and the file
+does not already exist, the C<tie> call will fail.
+
+=item 5.
+
+The default permissions to use if a new file is created. The actual
+permissions will be modified by the user's umask, so you should
+probably use 0666 here. (See L<perlfunc/umask>.)
+
+=back
+
+=head1 DIAGNOSTICS
+
+On failure, the C<tie> call returns an undefined value and probably
+sets C<$!> to contain the reason the file could not be tied.
+
+=head2 C<ndbm store returned -1, errno 22, key "..." at ...>
+
+This warning is emmitted when you try to store a key or a value that
+is too long. It means that the change was not recorded in the
+database. See BUGS AND WARNINGS below.
+
+=head1 BUGS AND WARNINGS
+
+There are a number of limits on the size of the data that you can
+store in the NDBM file. The most important is that the length of a
+key, plus the length of its associated value, may not exceed 1008
+bytes.
-See L<perlfunc/tie>, L<perldbmfilter>
+See L<perlfunc/tie>, L<perldbmfilter>, L<Fcntl>
=cut
=head1 SYNOPSIS
+ use Fcntl; # For O_RDWR, O_CREAT, etc.
use ODBM_File;
- tie(%h, 'ODBM_File', 'Op.dbmx', O_RDWR|O_CREAT, 0640);
+ # Now read and change the hash
+ $h{newkey} = newvalue;
+ print $h{oldkey};
+ ...
+
+ untie %h;
+
+=head1 DESCRIPTION
+
+C<ODBM_File> establishes a connection between a Perl hash variable and
+a file in ODBM_File format;. You can manipulate the data in the file
+just as if it were in a Perl hash, but when your program exits, the
+data will remain in the file, to be used the next time your program
+runs.
- untie %h;
+Use C<ODBM_File> with the Perl built-in C<tie> function to establish
+the connection between the variable and the file. The arguments to
+C<tie> should be:
-=head1 DESCRIPTION
+=over 4
+
+=item 1.
+
+The hash variable you want to tie.
+
+=item 2.
+
+The string C<"ODBM_File">. (Ths tells Perl to use the C<ODBM_File>
+package to perform the functions of the hash.)
+
+=item 3.
+
+The name of the file you want to tie to the hash.
+
+=item 4.
+
+Flags. Use one of:
+
+=over 2
+
+=item C<O_RDONLY>
+
+Read-only access to the data in the file.
+
+=item C<O_WRONLY>
+
+Write-only access to the data in the file.
+
+=item C<O_RDWR>
+
+Both read and write access.
+
+=back
+
+If you want to create the file if it does not exist, add C<O_CREAT> to
+any of these, as in the example. If you omit C<O_CREAT> and the file
+does not already exist, the C<tie> call will fail.
+
+=item 5.
+
+The default permissions to use if a new file is created. The actual
+permissions will be modified by the user's umask, so you should
+probably use 0666 here. (See L<perlfunc/umask>.)
+
+=back
+
+=head1 DIAGNOSTICS
+
+On failure, the C<tie> call returns an undefined value and probably
+sets C<$!> to contain the reason the file could not be tied.
+
+=head2 C<odbm store returned -1, errno 22, key "..." at ...>
+
+This warning is emmitted when you try to store a key or a value that
+is too long. It means that the change was not recorded in the
+database. See BUGS AND WARNINGS below.
+
+=head1 BUGS AND WARNINGS
+
+There are a number of limits on the size of the data that you can
+store in the ODBM file. The most important is that the length of a
+key, plus the length of its associated value, may not exceed 1008
+bytes.
-See L<perlfunc/tie>, L<perldbmfilter>
+See L<perlfunc/tie>, L<perldbmfilter>, L<Fcntl>
=cut
is too long. It means that the change was not recorded in the
database. See BUGS AND WARNINGS below.
-
-
=head1 BUGS AND WARNINGS
There are a number of limits on the size of the data that you can