Choose 'path' scheme when input is a TTY device

And there is no 'reload' action bound to 'start' event.

README.md

@@ -83,6 +83,7 @@ Table of Contents
     * [Custom fuzzy completion](#custom-fuzzy-completion)
 * [Vim plugin](#vim-plugin)
 * [Advanced topics](#advanced-topics)
+    * [Customizing for different types of input](#customizing-for-different-types-of-input)
     * [Performance](#performance)
     * [Executing external programs](#executing-external-programs)
     * [Turning into a different process](#turning-into-a-different-process)
@@ -718,6 +719,25 @@ See [README-VIM.md](README-VIM.md).
 Advanced topics
 ---------------
 
+### Customizing for different types of input
+
+Since fzf is a general-purpose text filter, its algorithm was designed to
+"generally" work well with any kind of input. However, admittedly, there is no
+true one-size-fits-all solution, and you may want to tweak the algorithm and
+some of the settings depending on the type of the input. To make this process
+easier, fzf provides a set of "scheme"s for some common types of input.
+
+| Scheme             | Description                                                                         |
+| :---               | :---                                                                                |
+| `--scheme=default` | Generic scheme designed to work well with any kind of input                         |
+| `--scheme=path`    | Suitable for file paths                                                             |
+| `--scheme=history` | Suitable for command history or any input where chronological ordering is important |
+
+(See `fzf --man` for the details)
+
+fzf heuristically chooses which scheme to use, but it will not always be
+perfect. If you see suboptimal behavior, try setting the scheme explicitly.
+
 ### Performance
 
 fzf is fast. Performance should not be a problem in most use cases. However,
@@ -727,6 +747,8 @@ you might want to be aware of the options that can affect performance.
   makes the initial scanning slower. So it's not recommended that you add it
   to your `$FZF_DEFAULT_OPTS`.
 - `--nth` makes fzf slower because it has to tokenize each line.
+- A plain string `--delimiter` should be preferred over a regular expression
+  delimiter.
 - `--with-nth` makes fzf slower as fzf has to tokenize and reassemble each
   line.
 

man/man1/fzf.1

@@ -91,6 +91,13 @@ more weight to the chronological ordering. This also sets
 .RE
 .RE
 
+.RS
+fzf chooses \fBpath\fR scheme when the input is a TTY device, where fzf would
+start its built-in walker or run \fB$FZF_DEFAULT_COMMAND\fR, and there is no
+\fBreload\fR action bound to \fBstart\fR event. Otherwise, it chooses
+\fBdefault\fR scheme.
+.RE
+
 .TP
 .BI "\-\-algo=" TYPE
 Fuzzy matching algorithm (default: v2)
@@ -1125,9 +1132,9 @@ Show man page
 .SH ENVIRONMENT VARIABLES
 .TP
 .B FZF_DEFAULT_COMMAND
-Default command to use when input is tty. On *nix systems, fzf runs the command
-with \fB$SHELL \-c\fR if \fBSHELL\fR is set, otherwise with \fBsh \-c\fR, so in
-this case make sure that the command is POSIX-compliant.
+Default command to use when input is a TTY device. On *nix systems, fzf runs
+the command with \fB$SHELL \-c\fR if \fBSHELL\fR is set, otherwise with \fBsh
+\-c\fR, so in this case make sure that the command is POSIX-compliant.
 .TP
 .B FZF_DEFAULT_OPTS
 Default options.

src/options.go

@@ -3225,7 +3225,14 @@ func ParseOptions(useDefaults bool, args []string) (*Options, error) {
 	if len(opts.Scheme) == 0 {
 		opts.Scheme = "default"
 		if len(opts.Criteria) == 0 {
-			if util.IsTty(os.Stdin) && len(os.Getenv("FZF_DEFAULT_COMMAND")) == 0 {
+			// NOTE: Let's assume $FZF_DEFAULT_COMMAND generates a list of file paths.
+			// But it is possible that $FZF_DEFAULT_COMMAND is set to a command that
+			// doesn't generate file paths.
+			//
+			// In that case, you can either
+			//   1. explicitly set --scheme=default,
+			//   2. or replace $FZF_DEFAULT_COMMAND with an equivalent start:reload binding.
+			if !opts.hasReloadOnStart() && util.IsTty(os.Stdin) {
 				opts.Scheme = "path"
 			}
 			_, opts.Criteria, _ = parseScheme(opts.Scheme)
@@ -3240,6 +3247,17 @@ func ParseOptions(useDefaults bool, args []string) (*Options, error) {
 	return opts, nil
 }
 
+func (opts *Options) hasReloadOnStart() bool {
+	if actions, prs := opts.Keymap[tui.Start.AsEvent()]; prs {
+		for _, action := range actions {
+			if action.t == actReload || action.t == actReloadSync {
+				return true
+			}
+		}
+	}
+	return false
+}
+
 func (opts *Options) extractReloadOnStart() string {
 	cmd := ""
 	if actions, prs := opts.Keymap[tui.Start.AsEvent()]; prs {