duodiff — compare and synchronize directory trees in the terminal

Every pair says what it is

The narrow column between the panes carries one mark per aligned pair. It says what the active scan established — and, just as importantly, what it did not.

▾ src/	≠	▾ src/	something below differs
theme.rs	=	theme.rs	no difference found
ui.rs	≈	ui.rs	unverified — the bytes were never compared
main.rs	≠	main.rs	a difference the scan established
notes.md	<	—	present on the left only
—	>	README.md	present on the right only
▸ build/	!	build	one side is a file, the other a directory

≈ is the honest answer when nothing read the bytes: in Fast mode the sizes match but the timestamps differ; in Precise mode a side could not be read or hashed. Switching to Precise mode with c resolves it.

What it does

Keys are listed in full in the shortcuts reference.

Two scan modes

Fast compares size and modification time; Precise compares a streaming SHA-256 of the contents. c switches and persists the choice; --scan-mode overrides it for one session.

Scans in the background

Alignment and checksums run off the render thread, with a live item count while a large tree is walked. Navigation stays responsive throughout.

Diff and merge in place

A side-by-side diff with intraline highlighting and next/previous jumps (N/P). Stage a change block to either side with [ and ], undo with u, then write every staged side with s.

Copy across panes

L and R copy a file or a whole directory between panes. Every copy previews both paths and asks first, then re-scans. A directory copy follows the scan's own entry list, so excluded paths stay out of it.

External tools

D hands the pair to vim, nvim, code, meld, bcomp, smerge, ksdiff, or difft; E opens the file in $VISUAL or $EDITOR. duodiff leaves the terminal cleanly and restores it on return.

Filter and exclusions

/ filters the whole scanned tree, flat, with breadcrumbs; Ctrl+f narrows it to differences. Each root's nested .gitignore and .duodiffignore are read by default, after a global exclusion list you can edit in place.

Vim keys and mouse

hjkl or the arrow keys, Ctrl+f and Ctrl+b to page, 1/2 to focus a pane. The wheel scrolls both panes together; a double-click opens a diff or expands a directory.

One command palette

;, Ctrl+p, or a right-click open the same searchable surface on every screen. A command that cannot run right now stays listed, carrying the reason it cannot.

Config that persists

A flat Config screen (C) detects installed diff tools and saves each change immediately to ~/.config/duodiff/config.toml. T toggles the light and dark theme from anywhere. Topic-based help is on ?.

>_ duodiff