ODBM_File(3perl)

💖 ODBM_File(3perl) 💖

okay bestie, pull up a chair, we're learning ODBM_File and honestly? it's giving "vintage database energy" ✨

🌸 NAME 🌸

ODBM_File — tied access to odbm files 💅

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🎀 SYNOPSIS 🎀

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

tie(%h, 'ODBM_File', 'filename.dbmx', O_RDWR|O_CREAT, 0640)
  or die "Couldn't tie ODBM file 'filename.dbmx': $!; aborting";

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

untie %h;

like… the die message is doing the most but honestly? correct. respect. 🫶

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✨ DESCRIPTION ✨

so ODBM_File establishes a connection between a Perl hash variable and a file in ODBM_File format (yes, with the little stray ; in the original, she's a little messy, we love her anyway 💀). You can manipulate the data in the file just as if it were in a Perl hash, BUT — and this is the main character twist — when your program exits, the data will remain in the file, to be used the next time your program runs. persistence!! we stan an enduring queen 👑

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". (this tells Perl to use the ODBM_File package to perform the functions of the hash — the original says "Ths" here, it's a typo, we're all human, moving on 💖)
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. look, don't touch 🙈
   • "O_WRONLY" — write-only access to the data in the file. touch, don't look 💅
   • "O_RDWR" — both read and write access. main character energy, you get both 🔥

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. no file, no vibes, no hash.

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.) 🌈

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😭 DIAGNOSTICS 😭

On failure, the "tie" call returns an undefined value and probably sets $! to contain the reason the file could not be tied. so like… always check, bestie. always. 🫶

"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. not saved. gone. See BUGS AND WARNINGS below 👇

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🔒 SECURITY AND PORTABILITY 🔒

Do not accept ODBM files from untrusted sources. like, seriously, don't. this is not a drill. 💀

On modern Linux systems these are typically GDBM files, which are not portable across platforms.

The GDBM documentation doesn't imply that files from untrusted sources can be safely used with "libgdbm".

Systems that don't use GDBM compatibility for old dbm support will be using a platform specific library, possibly inherited from BSD systems, where it may or may not be safe to use an untrusted file.

A maliciously crafted file might cause perl to crash or even expose a security vulnerability. not cute. not slay. please be careful. 🥺

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💀 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. that's it. that's the ceiling. the math is not mathing past 1008, periodt. 📏

See "tie" in perlfunc, perldbmfilter, Fcntl 👑

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kisses, babe — this was ODBM_File(3perl) from the Perl Programmers Reference Guide, version perl v5.44.0, dated 2026-10-17. go tie a hash, hydrate, and text me back 💜🧚‍♀️