THISCELL(5)

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💖 THISCELL(5) — the ThisCell file, bestie edition 💖

AFS File Reference ✨ okay so this is the manual for ThisCell, and no cap, it's a tiny file with big main character energy. Let's get into it. 🦋

🌸 NAME 🌸

ThisCell — it defines the local cell name, periodt. 💅

✨ DESCRIPTION ✨

So the ThisCell file is literally just... the name of your local cell. That's it. That's the whole job. 🎀

But listen — there are TWO versions of this file, and you gotta know which one you're dealing with:

  • one for an AFS client 🫶
  • one for an AFS server 👑

Let's talk about both, bestie. 🧚

🦋 Client ThisCell 🦋

The client version of the ThisCell file defines the complete Internet domain-style name of the cell that the local client machine belongs to — like, for example, "example.com". 🌈

It MUST live in the /etc/openafs directory on every single AFS client machine. Every one. No skipping. 🙅‍♀️

Wanna change a client machine's cell membership? Edit the file and reboot the machine. That's the move. 🔄

The file is in ASCII format and contains a character string on a single line (one line, bestie, don't get fancy). The OpenAFS Quick Start Guide tells the administrator to create it during the installation of each client machine. 📝

So here's the thing — the client machine's cell membership determines THREE DEFAULTS that are super important to how it functions:

  • The cell in which the machine's users authenticate by default. And the effect is twofold, so buckle up:
    • The AFS-modified login utilities and the klog command interpreter contact an Authentication Server in the cell named in the ThisCell file — unless the -cell argument to the klog command specifies an alternate cell. 🎯
    • The command interpreters combine the cell name with the password that the user provides, generating an encryption key from the combination. For authentication to succeed, both the cell name and the password must match the ones used to generate the user's encryption key stored in the Authentication Database. Both. Or it's not happening. 💀
  • The cell the Cache Manager considers its local, or home, cell. By default, the Cache Manager allows programs that reside in its home cell to run with setuid permission — but NOT programs from foreign cells. For more details, see the fs getcellstatus and fs setcell reference pages. 👀
  • Which AFS server processes the local AFS command interpreters contact by default as they execute commands issued on the machine. 🖥️

K so — the client version of the ThisCell file is distinct from the server version, which lives in the /etc/openafs/server directory on each AFS server machine. If a server machine also runs as a client, it's totally acceptable for the server and client versions of the file on the same machine to name different cells. 👯

However — the behavior that results from this configuration can be more confusing than useful. 🙈 So like... you can, but should you? That's on you.

👑 Server ThisCell 👑

The server version of the ThisCell file defines the complete Internet domain-style name of the cell that the server machine belongs to — again, something like "example.com". ✨

It MUST live in the /etc/openafs/server directory on every AFS server machine. 🏠

The file is in ASCII format and contains a character string on a single line. The initial version of the file is created with the bos setcellname command during the installation of the cell's first file server machine, and the OpenAFS Quick Start Guide includes instructions for copying it over to additional server machines during their installation. 📦

Now, the only reason to edit this file is as part of changing the cell's name — and ngl, that is strongly discouraged because of the huge number of configuration changes involved. 😭 Like, it's giving "do not attempt."

In particular: changing the cell name requires rebuilding the entire Authentication Database, because the Authentication Server combines the cell name it finds in this file with each user and server password and converts the combination into an encryption key before recording it in the Database. So yeah. Whole database. From scratch. 💀

💜 SEE ALSO 💜

IBM Corporation 2000. <http://www.ibm.com/> All Rights Reserved.

This documentation is covered by the IBM Public License Version 1.0. It was converted from HTML to POD by software written by Chas Williams and Russ Allbery, based on work by Alf Wachsmann and Elizabeth Cassell. 👑

And that's the whole page, bestie — slayed. 💅✨

OpenAFS 🌸 2026-07-27 🦋 THISCELL(5) — mwah, love u, go read your config files. 💖

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