lesser 0.1.0

A lesser pager (even less than less), for everyday use
lesser-0.1.0 is not a library.

lesser

A lesser pager, even less than less. Implemented in Rust.

It aims to be a drop-in replacement for less in everyday use — git, man, systemd-journald — without the long tail of features almost nobody touches. It is a clean-room reimplementation derived from the less(1) man page and observed runtime behavior; no less source was read.

Install

From source:

cargo install lesser

Use

Just like less:

git diff --color=always | lesser -R
man ls | lesser
ls -la | lesser
lesser src/main.rs

lesser reads the LESS and SYSTEMD_LESS environment variables and accepts their bundled-flag form (LESS=FRX, SYSTEMD_LESS=FRSXMK). Flags that aren't implemented yet are silently ignored, never errored — set it as $PAGER and expect things to work.

LESS=FRX (git's default) is the canary configuration this is built for.

Keys

Navigation:

Key Action
q quit
space, PgDn page down
b, PgUp page up
j, ↓, Enter next visual row
k, ↑ previous visual row
g, Home first row
G, End last row

Search:

Key Action
/ start search; matches highlight as you type
Enter commit pattern and jump to first match
Esc, ctrl-c cancel
Backspace erase char (empty input + Backspace exits)
n next match (wraps around)

Display:

Key Action
S toggle chop / wrap

Flags

Flag Behavior
-R pass ANSI color escapes through
-F quit if the input fits one screen
-X skip alternate screen (output stays in scrollback on exit)
-S start in chop mode (default is wrap; toggle with S at runtime)
-K quit on ctrl-c (accepted; not yet wired in)

What works

  • Stdin and file input
  • -R ANSI passthrough — colored git diff renders correctly, with per-line SGR reset to prevent color bleed
  • -F quit-if-one-screen — git log -1 doesn't pop a pager for two lines
  • -X no-init — output stays in scrollback after exit
  • Wrap (default) and chop modes, with runtime S toggle
  • Smooth visual scrolling: a wrapped line advances one visual row at a time, not one logical line
  • Resize handling: SIGWINCH rebuilds the visual layout while preserving the user's logical-line position
  • Regex search with live highlighting as you type, wrap-around, n for next match
  • LESS / SYSTEMD_LESS env-var bundles parsed; unknown flags ignored
  • Unicode display widths (CJK characters take two columns and chop/wrap correctly)

What doesn't (yet)

  • -K (quit on ctrl-c) is accepted but not wired in
  • Backspace-overstrike decoding for older man output (_\bx underline, x\bx bold) is not implemented
  • Without -R, ANSI escapes pass through as-is rather than being shown literally as ^[[31m (less's default)
  • No marks, tags, ! shell escape, +cmd
  • No multi-file navigation (:n / :p)
  • No LESSOPEN preprocessors
  • No hex mode
  • No reverse search ?, no <num>g jump-to-line

These map to the roadmap and explicit non-goals in PLAN.md.

Targets

Linux and macOS, primarily. Should work on other Unix-likes; not actively tested. Windows is best-effort and currently untested.

License

MIT or Apache-2.0, at your convenience.