Configuration

fzf reads configuration from environment variables, an optional defaults file, and command-line flags. The CLI flags always win.

Defaults pipeline

1. FZF_DEFAULT_OPTS_FILE — if set, read flags from this file (one shell-style argument per token, comments allowed).
2. FZF_DEFAULT_OPTS — additional flags as a single string, parsed with go-shellwords.
3. Command-line os.Args[1:] — final overrides.

Implemented near the top of ParseOptions in src/options.go.

Core environment variables

Variable	Purpose
FZF_DEFAULT_COMMAND	Command to run when stdin is a TTY (instead of the built-in walker).
FZF_DEFAULT_OPTS	Shell-style default flags.
FZF_DEFAULT_OPTS_FILE	Path to a defaults file.
FZF_API_KEY	API key for non-localhost --listen.

Shell integration variables

These are consumed by the embedded shell scripts, not the Go binary:

Variable	Purpose
FZF_CTRL_T_COMMAND, FZF_CTRL_T_OPTS	Override Ctrl-T behavior.
FZF_CTRL_R_COMMAND, FZF_CTRL_R_OPTS	Override Ctrl-R behavior.
FZF_ALT_C_COMMAND, FZF_ALT_C_OPTS	Override Alt-C behavior.
FZF_COMPLETION_TRIGGER	Trigger sequence for fuzzy completion (** by default).
FZF_COMPLETION_OPTS	Default flags for completion fzf invocations.
FZF_COMPLETION_PATH_OPTS, FZF_COMPLETION_DIR_OPTS	Per-source overrides.
FZF_TMUX, FZF_TMUX_HEIGHT, FZF_TMUX_OPTS	Auto-route through fzf-tmux.

The exact lookup is in shell/key-bindings.{bash,zsh,fish} and shell/completion.{bash,zsh,fish}.

Display environment

Variable	Effect
TERM	Picked up by the renderer; affects color and capability assumptions.
LANG / LC_ALL	Affect grapheme width calculations via github.com/rivo/uniseg.
COLUMNS / LINES	Used when the renderer can't query the TTY directly.
NO_COLOR	Disables color output if the user has set it.

Scoring schemes

--scheme=PRESET selects a preset:

• default — general-purpose.
• path — tuned for paths; gives extra bonus after /.
• history — tuned for shell history; disables sort by score.

Implementation in src/algo/algo.go (the bonusBoundary* constants and Scheme selection in BuildPattern).

Tiebreakers

--tiebreak=A,B,C applies the listed criteria in order when scores tie. Available values: length, chunk, pathname, begin, end, index. Defined in src/options.go (byLength, byChunk, ...) and consumed by Result.Less in src/result.go.

Style presets

--style=PRESET[:BORDER_STYLE] is a one-line way to set borders, padding, and margin together:

• default — minimal frame.
• minimal — strip everything to the essentials.
• full — full borders and labels everywhere.

Implementation in src/options.go (parseStyle) and src/terminal.go (border / padding / margin layout).

Color theme

--color=base[,FIELD:COLOR]* configures the palette. base is one of dark, light, base16, bw. The full color spec language is documented in the man page; parsing happens in src/options.go (parseTheme).

History

--history=FILE enables an editable, fzf-managed history of queries. Implementation in src/history.go.

Walker options

Flag	Default	Notes
--walker=file,dir,follow,hidden	file,follow,hidden=false	Pass dir to include directories, follow to follow symlinks (with the loop guard in src/reader.go), hidden to include dotfiles.
--walker-root=DIR[,DIR...]	.	Roots to walk.
--walker-skip=NAME[,NAME...]	empty	Directory names or paths to skip.

These compose with FZF_DEFAULT_COMMAND: if both are set, FZF_DEFAULT_COMMAND wins for the initial read, but the walker is used for subsequent reload actions that don't specify a command.

Profiling

When built with -tags pprof:

• --profile-cpu PATH
• --profile-mem PATH
• --profile-block PATH
• --profile-mutex PATH

Implementation in src/options_pprof.go.