kovidgoyal/kitty · warning

Usage: __atexit__

Error message

Usage: __atexit__

What it means

The atexit tool was invoked with unexpected command-line arguments: its CLI wrapper recognized no valid subcommand/flag combination, so it bails with the usage message 'Usage: __atexit__'. It is a pure argument-validation error — nothing ran yet.

Source

Thrown at tools/cmd/atexit/main.go:95

	}
	return
}

func EntryPoint(root *cli.Command) {
	root.AddSubCommand(&cli.Command{
		Name:            "__atexit__",
		Hidden:          true,
		OnlyArgsAllowed: true,
		Run: func(cmd *cli.Command, args []string) (rc int, err error) {
			if len(args) != 0 {
				if args[0] == "test" {
					rc = 0
					if err = do_test(); err != nil {
						rc = 1
					}
					return
				}
				return 1, fmt.Errorf("Usage: __atexit__")
			}
			return main()
		},
	})
}

View on GitHub (pinned to 6d5d0c4406)

Solutions

1. Run the tool with no arguments or --help to list valid subcommands
2. Fix the typo/order of the first argument to a registered subcommand
3. If a script breaks after an upgrade, diff the tool's help output against what the script passes

Example fix

# before
__atexit__ testt
# after
__atexit__ test

// Validate argv before invoking the tool
valid := map[string]bool{"test": true /* other real subcommands */}
if len(os.Args) > 1 && !valid[os.Args[1]] {
    fmt.Fprintln(os.Stderr, "Usage: __atexit__"); os.Exit(2)
}

// Shell wrapper
if ! __atexit__ "$cmd" 2>/dev/null; then
    echo "unknown subcommand: $cmd" >&2; __atexit__ --help
fi

When it happens

Trigger: Running the atexit binary with arguments that don't match any registered subcommand (e.g. a typo'd or unsupported first argument), so argument parsing falls through to the usage-error return in main.go:95.

Common situations: Typos in subcommand names, passing flags before/without the subcommand, scripts written against an older version whose subcommands were renamed, or copy-pasting an invocation from docs of a different tool.

Related errors

• Usage: kitty +runpy "some python code"
• usage: kitty +launch script.py [arguments to be passed to sc
• Unknown extra argument(s) supplied to {command.name}
• must specify the new contrast value
• must specify the key

AI-assisted analysis of kovidgoyal/kitty@6d5d0c4406 (2026-08-27). Data as JSON: /api/errors/f2d5e73fdb0714d6. Report an issue: GitHub.