Allow users to generate man pages

Cargo.toml

@@ -49,6 +49,7 @@ xdg = "3.0.0"
 xml-rs = "0.8.20"
 xz2 = "0.1.7"
 zstd = { version = "0.13.3", features = [ "zstdmt" ] }
+clap_mangen = "0.2.28"
 
 [dependencies.tokio]
 features = ["full"]

flake.nix

@@ -33,6 +33,7 @@
             lockFile = ./Cargo.lock;
           };
 
+          nativeBuildInputs = [ installShellFiles ];
           buildInputs = [ sqlite ];
 
           postInstall = ''
@@ -42,6 +43,12 @@
             substituteInPlace command-not-found.nu \
               --subst-var out
             install -Dm555 command-not-found.nu -t $out/etc/profile.d
+
+            "$out/bin/nix-locate" --mangen > nix-locate.1
+            "$out/bin/nix-index" --mangen > nix-index.1
+            "$out/bin/nix-channel-index" --mangen > nix-channel-index.1
+
+            installManPage nix-locate.1 nix-index.1 nix-channel-index.1
           '';
 
           meta = with lib; {

src/bin/nix-channel-index.rs

@@ -175,7 +175,7 @@ async fn update_index(args: &Args) -> Result<()> {
 }
 
 #[derive(Debug, Parser)]
-#[clap(author, about, version)]
+#[clap(author, about, version, name = "nix-channel-index")]
 struct Args {
     /// Make REQUESTS http requests in parallel
     #[clap(short = 'r', long = "requests", default_value = "500")]
@@ -200,12 +200,28 @@ struct Args {
     /// Show a stack trace in the case of a Nix evaluation error
     #[clap(long)]
     show_trace: bool,
+
+    /// Generate man page, then exit.
+    #[clap(long, hide = true)]
+    mangen: bool,
 }
 
 #[tokio::main]
 async fn main() {
     let args = Args::parse();
 
+    if args.mangen {
+        use clap::CommandFactory;
+        let man = clap_mangen::Man::new(Args::command());
+
+        if let Err(err) = man.render(&mut std::io::stdout()) {
+            eprintln!("error: {}", err);
+            process::exit(2)
+        } else {
+            return;
+        }
+    }
+
     if let Err(e) = update_index(&args).await {
         eprintln!("error: {:?}", e);
         process::exit(2);

src/bin/nix-index.rs

@@ -132,7 +132,7 @@ fn cache_dir() -> &'static OsStr {
 
 /// Builds an index for nix-locate
 #[derive(Debug, Parser)]
-#[clap(author, about, version)]
+#[clap(author, about, version, name = "nix-index")]
 struct Args {
     /// Make REQUESTS http requests in parallel
     #[clap(short = 'r', long = "requests", default_value = "100")]
@@ -168,12 +168,28 @@ struct Args {
     /// Note: does not check if the cached data is up to date! Use only for development.
     #[clap(long)]
     path_cache: bool,
+
+    /// Generate man page, then exit
+    #[clap(long, hide = true)]
+    mangen: bool,
 }
 
 #[tokio::main]
 async fn main() {
     let args = Args::parse();
 
+    if args.mangen {
+        use clap::CommandFactory;
+        let man = clap_mangen::Man::new(Args::command());
+
+        if let Err(err) = man.render(&mut std::io::stdout()) {
+            eprintln!("error: {}", err);
+            process::exit(2)
+        } else {
+            return;
+        }
+    }
+
     if let Err(e) = update_index(&args).await {
         eprintln!("error: {:?}", e);
         process::exit(2);

src/bin/nix-locate.rs

@@ -180,7 +180,7 @@ fn locate(args: &Args) -> Result<()> {
 ///
 /// Handles parsing the values of more complex arguments.
 fn process_args(matches: Opts) -> result::Result<Args, clap::Error> {
-    let pattern_arg = matches.pattern;
+    let pattern_arg = matches.pattern.unwrap();
     let package_arg = matches.package;
 
     let start_anchor = if matches.at_root { "^" } else { "" };
@@ -260,11 +260,11 @@ fn cache_dir() -> &'static OsStr {
 
 /// Quickly finds the derivation providing a certain file
 #[derive(Debug, Parser)]
-#[clap(author, about, version, after_help = LONG_USAGE)]
+#[clap(author, about, version, after_help = LONG_USAGE, name = "nix-locate")]
 struct Opts {
     /// Pattern for which to search
-    // #[clap(name = "PATTERN")]
-    pattern: String,
+    #[clap(required_unless_present = "mangen", name = "PATTERN")]
+    pattern: Option<String>,
 
     /// Directory where the index is stored
     #[clap(short, long = "db", default_value_os = cache_dir(), env = "NIX_INDEX_DATABASE")]
@@ -320,6 +320,10 @@ struct Opts {
     /// store path are omitted. This is useful for scripts that use the output of nix-locate.
     #[clap(long)]
     minimal: bool,
+
+    /// Generate the man page, then exit
+    #[clap(long, hide = true)]
+    mangen: bool,
 }
 
 #[derive(clap::ValueEnum, Clone, Copy, Debug)]
@@ -345,6 +349,18 @@ impl FromStr for Color {
 fn main() {
     let args = Opts::parse();
 
+    if args.mangen {
+        use clap::CommandFactory;
+        let man = clap_mangen::Man::new(Opts::command());
+
+        if let Err(e) = man.render(&mut std::io::stdout()) {
+            eprintln!("error: {}", e);
+            process::exit(2)
+        } else {
+            return;
+        }
+    }
+
     let args = process_args(args).unwrap_or_else(|e| e.exit());
 
     if let Err(e) = locate(&args) {