The settings window is small on purpose, and a dozen further behaviours are adjustable with defaults write com.knollsoft.Rectangle. Every one of them loads when the app starts, so each change needs a restart of the app to take effect. Nothing here is dangerous and everything is reversible.
How this works, and the one rule
Configuration is stored with the standard macOS preferences system, in a file at ~/Library/Preferences/com.knollsoft.Rectangle.plist. Terminal writes values into it directly, which is how options that never got an interface remain adjustable.
The rule that catches everyone: these values are read when the app launches. Run a command, see no change, conclude it did not work — the app simply has not reloaded. Quit it and start it again after every write.
To read a value rather than set one, swap write for read. To remove a single key and return to the built-in behaviour, use defaults delete with the same key name.
The repeated-execution mode
The most consequential setting on this page decides what a second press of the same shortcut does.
defaults write com.knollsoft.Rectangle subsequentExecutionMode -int 2
The integer selects a behaviour. Zero gives the Spectacle-style progression from halves to thirds. One sends the window to an adjacent display on repeated left or right commands. Two disables repetition entirely, so a shortcut always produces the same result. Three combines display cycling for the arrow commands with size cycling for everything else. Four repeats the same action on the next display.
Two is the value to know. Anyone irritated by a window changing size because they pressed a key twice wants repetition off, and no checkbox in the settings window offers exactly that.
Resize steps and minimum sizes
The incremental commands move a window edge by a fixed number of pixels, and the step is adjustable.
defaults write com.knollsoft.Rectangle sizeOffset -float 30
Thirty is the shipped value on every Rectangle Mac build. On a large display it is too small to be efficient, and doubling it turns four presses into two. On a laptop the default is about right.
The shrink command also has a floor, expressed as a fraction of the screen rather than in pixels, below which a window will not go. Two keys govern width and height separately, taking a value between zero and one, with a quarter of the screen as the shipped limit. Lower them if a genuinely small window is ever wanted; leave them alone otherwise.
Gaps, directional moves and shortcut presets
defaults write com.knollsoft.Rectangle gapSize -float 10 sets padding between tiled windows. This one has a caveat worth stating plainly: gap size moved into the settings window in recent versions, so the graphical control is the right route now and the command survives as a fallback.
Directional moves centre a window along the edge it moves toward, and that centring can be switched off with centeredDirectionalMove. Useful for anyone who wants a window pushed to an edge without it sliding sideways at the same time.
defaults write com.knollsoft.Rectangle alternateDefaultShortcuts -bool true chooses between the two shipped shortcut sets — true for the recommended layout, false for the Spectacle one. Handy for scripting a machine setup, since it means a fresh install can be configured without touching the interface. The Rectangle app documents the full list in its repository.
Undoing everything
defaults delete com.knollsoft.Rectangle removes every stored preference and returns the app to a first-launch state, shortcuts included.
Export the configuration to JSON from the settings window first if any of it is worth keeping. That file also makes these commands unnecessary for most transfers — export, import, done, with no Terminal involved at all.
One footnote for anyone running the paid application: it uses a different preferences domain, so the same command names apply to a different identifier. Mixing the two silently writes settings that nothing reads. Both are covered on the official Rectangle site, and the free Mac window manager keeps its own domain unchanged across versions.
Frequently asked questions
Can these commands break anything?
Nothing outside the app itself. Every key affects only its own preferences file, and deleting that file returns everything to defaults. The worst outcome is a behaviour you dislike until you change it back.
Do I need administrator rights?
No. The preferences file lives in your own home folder, so no elevation is involved and no password is requested. Anything demanding one for this is not what it claims to be.
Why isn’t this in the settings window?
The interface is kept deliberately narrow so the app stays simple for the majority who never need these options. Settings graduate into the window when enough people want them, which is what happened with gap size.
Will an update overwrite my changes?
Updates preserve the preferences file, so custom values survive. A key that a release stops reading is silently ignored rather than removed, which is why re-checking a configuration after a major update is worth ten minutes.
