Generate man page with help2man (#463)

The generated man page doesn't look great by default, so this also adds the
help4help2man feature, which makes Just print a help message that produces
a better man page.

Cargo.toml

@@ -8,6 +8,10 @@ homepage    = "https://github.com/casey/just"
 readme      = "crates-io-readme.md"
 edition     = "2018"
 
+[features]
+default = []
+help4help2man = []
+
 [dependencies]
 ansi_term      = "0.11"
 assert_matches = "1"

justfile

@@ -36,6 +36,16 @@ check:
 watch +COMMAND='test':
 	cargo watch --clear --exec "{{COMMAND}}"
 
+man:
+	cargo build --features help4help2man
+	help2man \
+		--name 'save and run commands' \
+		--manual 'JUST MANUAL' \
+		--no-info \
+		target/debug/just \
+		> man/just.1
+	man man/just.1
+
 version := `sed -En 's/version[[:space:]]*=[[:space:]]*"([^"]+)"/v\1/p' Cargo.toml | head -1`
 
 # publish to crates.io
@@ -70,6 +80,10 @@ install-dev-deps:
 	cargo install -f cargo-check
 	cargo +nightly install cargo-fuzz
 
+# install system development dependencies with homebrew
+install-dev-deps-homebrew:
+	brew install help2man
+
 # everyone's favorite animate paper clip
 clippy:
 	cargo clippy

man/just.1

@@ -0,0 +1,70 @@
+.\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.47.10.
+.TH JUST "1" "July 2019" "just 0.4.4" "JUST MANUAL"
+.SH NAME
+just \- save and run commands
+.SH DESCRIPTION
+just 0.4.4
+\- Please see https://github.com/casey/just for more information.
+.SS "USAGE:"
+.IP
+just [FLAGS] [OPTIONS] [\-\-] [ARGUMENTS]...
+.SS "FLAGS:"
+.TP
+\fB\-\-dry\-run\fR
+Print what just would do without doing it
+.TP
+\fB\-\-dump\fR
+Print entire justfile
+.TP
+\fB\-e\fR, \fB\-\-edit\fR
+Open justfile with $EDITOR
+.TP
+\fB\-\-evaluate\fR
+Print evaluated variables
+.TP
+\fB\-\-highlight\fR
+Highlight echoed recipe lines in bold
+.TP
+\fB\-l\fR, \fB\-\-list\fR
+List available recipes and their arguments
+.TP
+\fB\-q\fR, \fB\-\-quiet\fR
+Suppress all output
+.TP
+\fB\-\-summary\fR
+List names of available recipes
+.TP
+\fB\-v\fR, \fB\-\-verbose\fR
+Use verbose output
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+Print help information
+.TP
+\fB\-V\fR, \fB\-\-version\fR
+Print version information
+.SS "OPTIONS:"
+.HP
+\fB\-\-color\fR <COLOR>
+.TP
+Print colorful output [default: auto]
+[possible values: auto, always, never]
+.TP
+\fB\-f\fR, \fB\-\-justfile\fR <JUSTFILE>
+Use <JUSTFILE> as justfile.
+.TP
+\fB\-\-set\fR <VARIABLE> <VALUE>
+Set <VARIABLE> to <VALUE>
+.TP
+\fB\-\-shell\fR <SHELL>
+Invoke <SHELL> to run recipes [default: sh]
+.TP
+\fB\-s\fR, \fB\-\-show\fR <RECIPE>
+Show information about <RECIPE>
+.HP
+\fB\-d\fR, \fB\-\-working\-directory\fR <WORKING\-DIRECTORY>
+.IP
+Use <WORKING\-DIRECTORY> as working directory. \fB\-\-justfile\fR must also be set
+.SS "ARGS:"
+.TP
+<ARGUMENTS>...
+The recipe(s) to run, defaults to the first recipe in the justfile

src/run.rs

@@ -36,14 +36,7 @@ pub fn run() {
   let invocation_directory =
     env::current_dir().map_err(|e| format!("Error getting current directory: {}", e));
 
-  let matches = App::new(env!("CARGO_PKG_NAME"))
-    .version(concat!("v", env!("CARGO_PKG_VERSION")))
-    .author(env!("CARGO_PKG_AUTHORS"))
-    .about(concat!(
-      env!("CARGO_PKG_DESCRIPTION"),
-      " - ",
-      env!("CARGO_PKG_HOMEPAGE")
-    ))
+  let app = App::new(env!("CARGO_PKG_NAME"))
     .help_message("Print help information")
     .version_message("Print version information")
     .setting(AppSettings::ColoredHelp)
@@ -160,8 +153,26 @@ pub fn run() {
       "SUMMARY",
       "ARGUMENTS",
       "EVALUATE",
-    ]))
-    .get_matches();
+    ]));
+
+  let app = if cfg!(feature = "help4help2man") {
+    app.version(env!("CARGO_PKG_VERSION")).about(concat!(
+      "- Please see ",
+      env!("CARGO_PKG_HOMEPAGE"),
+      " for more information."
+    ))
+  } else {
+    app
+      .version(concat!("v", env!("CARGO_PKG_VERSION")))
+      .author(env!("CARGO_PKG_AUTHORS"))
+      .about(concat!(
+        env!("CARGO_PKG_DESCRIPTION"),
+        " - ",
+        env!("CARGO_PKG_HOMEPAGE")
+      ))
+  };
+
+  let matches = app.get_matches();
 
   let color = match matches.value_of("COLOR").expect("`--color` had no value") {
     "auto" => Color::auto(),