CONTENTS

• NAME
• SYNOPSIS
• DESCRIPTION
• DIAGNOSTICS
  • ndbm store returned -1, errno 22, key "..." at ...
• BUGS AND WARNINGS

#NAME

NDBM_File - Tied access to ndbm files

#SYNOPSIS

use Fcntl;   # For O_RDWR, O_CREAT, etc.use NDBM_File;# Now read and change the hash$h{newkey} = newvalue;print $h{oldkey}; ...untie %h;

#DESCRIPTION

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.

UseNDBM_File with the Perl built-intie function to establish the connection between the variable and the file. The arguments totie should be:

1. The hash variable you want to tie.

2. The string"NDBM_File". (Ths tells Perl to use theNDBM_File package to perform the functions of the hash.)

3. The name of the file you want to tie to the hash.

4. Flags. Use one of:

   #O_RDONLY

   Read-only access to the data in the file.

   #O_WRONLY

   Write-only access to the data in the file.

   #O_RDWR

   Both read and write access.

   If you want to create the file if it does not exist, addO_CREAT to any of these, as in the example. If you omitO_CREAT and the file does not already exist, thetie call will fail.

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"umask" in perlfunc.)

#DIAGNOSTICS

On failure, thetie call returns an undefined value and probably sets$! to contain the reason the file could not be tied.

#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.

#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"tie" in perlfunc,perldbmfilter,Fcntl

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