rel(4)

✨ NAME ✨

ok so this is the manual page for rel — the Release resource file 💖 (yes bestie, it's an Erlang module definition page, and it's lowkey iconic)

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🌸 DESCRIPTION 🌸

the release resource file is the girl who decides which applications are included in a release (system) based on Erlang/OTP. she's the guest list, she's the bouncer, she's everything 💅

this file gets used by the functions in systools when generating start scripts (.script, .boot) and release upgrade files (relup). so like, she's not just pretty, she works.

🎀 File Syntax 🎀

ok so the release resource file has GOT to be called Name.rel. that's the rule. no cap. 🦋

inside, the .rel file contains one single Erlang term, and that term is called a release specification. one term. that's it. and the file has this syntax:

{release, {RelName,Vsn}, {erts, EVsn},
  [{Application, AppVsn} |
   {Application, AppVsn, Type} |
   {Application, AppVsn, IncApps} |
   {Application, AppVsn, Type, IncApps}]}.

now lemme break down every single piece, because we do NOT skip details in this house 🙈✨

• RelName = string() — the release name. she's the title, the main character energy of the whole thing 👑
• Vsn = string() — the release version.
• EVsn = string() — the ERTS version this release is intended for.
• Application = atom() — the name of an application included in the release.
• AppVsn = string() — the version of an application included in the release.
• Type = permanent | transient | temporary | load | none — the start type of an application included in the release. and here's the tea ☕:
  • if Type = permanent | transient | temporary, the application is loaded and started in the corresponding way — go peek at application for the deets.
  • if Type = load, the application is only loaded.
  • if Type = none, the application is not loaded and not started, although the code for its modules is loaded. (so like, she's at the party but she's not talking to anyone 💀)
  • this defaults to permanent ✨
• IncApps = [atom()] — a list of applications that are included by an application included in the release. the list must be a subset of the included applications specified in the application resource file (Application.app) and overrides this value. defaults to the same value as in the application resource file. periodt.

⚠️ NOTE, and bestie this one MATTERS: the list of applications must contain the Kernel and STDLIB applications. like, mandatory mandatory. no Kernel, no STDLIB, no release. don't do it 🫶

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💜 See Also 💜

• application
• relup(4)
• systools

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that's the whole page bestie, you ate that 🌈⭐

Ericsson AB made this one — it's from sasl 4.4, and yeah it's the rel(4) page, so go forth and build your release, you absolute queen 🎀👑💖