File Association¶
Register OctoEdit as a handler for the file types you choose, so
double-clicking a .cpp, .md or .log in your file manager opens it here.
Everything lives on one Preferences page: Preferences ▸ File Associations.
How it works¶
The page shows a tree of common file types, grouped by family (C / C++ / Objective-C, JVM & .NET, Web, Scripting, Data & Config, Markup & Docs, Plain text & Logs). Tick a whole language, a whole category, or individual extensions — parents roll up to a partially-checked state.
A Custom node lets you add any extension the catalog doesn't list: type it
(with or without the leading dot — cpp, .CPP and .cpp all normalize to
.cpp) and press Add.
Press OK / Apply and the plugin registers the selected types with the operating system.
The page mirrors the system¶
The ticks are not a remembered choice — they are read from the operating system every time the page opens, and again whenever you come back to the window after visiting the system settings. Whatever the system says is what you see, so a registration changed outside OctoEdit (by another application's installer, by a hand edit, by an OS cleanup) shows up here immediately, and ticking the type again repairs it.
The Status column says what the system currently does with each type:
| Status | Meaning |
|---|---|
| Default | OctoEdit opens this type when you double-click a file. |
| Listed in "Open with" | The system offers OctoEdit for this type, but another application opens it by default. When it can name that application it does — Listed in "Open with" — default: Notepad. |
| Not registered | The system does not offer OctoEdit for this type. The current default is still named when the system knows one. |
What a tick means depends on the platform, and the note under the tree says which one you are on:
- Windows — ticking registers OctoEdit as an option for the type. Use "Set as default in Windows…" to make it the default; Windows does not let any application take a default silently.
- macOS — ticking makes OctoEdit the default application for the type straight away.
The OS confirms the final default
Modern Windows does not let any application silently make itself the default handler. Applying the page registers OctoEdit as a candidate — it appears in every ticked type's "Open with" list and in the Default apps page. The "Set as default in Windows…" button then deep-links you to the system's Default Apps UI, where you confirm the default yourself. Unticking a type removes the registration again.
On macOS, Launch Services applies the association directly (the system may show a one-time consent prompt).
| Platform | Support |
|---|---|
| Windows 10 / 11 | Registers per-user (no administrator rights needed) + opens the Default Apps UI. |
| macOS | Makes OctoEdit the default application for the type through Launch Services; unticking hands the type back to the application that had it before. |
| Linux | Not supported yet — the page explains this and stays informational. |
Settings¶
The plugin remembers only the custom extensions you added — the system
cannot remember an extension it does not associate, so a .conf you typed in
and left unticked would otherwise disappear. Everything else comes from the
system.
Registrations are written only when you press Apply on this page — the editor never re-registers file types behind your back at startup, so a default application you pick later somewhere else stays the default. If an OS cleanup or a profile migration ever drops a registration, the page shows that type unticked and Not registered; tick it and press Apply to put it back.
Related¶
- Workspace — open a whole folder inside the editor instead.
- Command line — opening files from
a shell, including the
file.txt:42go-to-line syntax.