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

# NAME

ODBM_File - Tied access to odbm files

# SYNOPSIS

     use Fcntl;   # For O_RDWR, O_CREAT, etc.
     use ODBM_File;

      # Now read and change the hash
      $h{newkey} = newvalue;
      print $h{oldkey};
      ...

      untie %h;

# DESCRIPTION

`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.

Use `ODBM_File` with the Perl built-in `tie` function to establish the connection between the variable and the file. The arguments to `tie` should be:

1. The hash variable you want to tie.

2. The string `"ODBM_File"`. (Ths tells Perl to use the `ODBM_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, add `O_CREAT` to any of these, as in the example. If you omit `O_CREAT` and the file does not already exist, the `tie` 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, the `tie` call returns an undefined value and probably sets `$!` to contain the reason the file could not be tied.

## `odbm store returned -1, errno 22, key "..." at ...`

This warning is emitted 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 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 "tie" in perlfunc, perldbmfilter, Fcntl