Linux package: mpftp with arguments is the CLI, not the window

desktop/README.md

@@ -22,7 +22,9 @@ installers next to the wheel and the VS Code extension:
   settings and logs too.
 - **Debian, Ubuntu and their relatives:** `mpftp_<version>_amd64.deb`, which
   uses the system's WebKitGTK. Install it with
-  `sudo apt install ./mpftp_<version>_amd64.deb` and start `mpftp`.
+  `sudo apt install ./mpftp_<version>_amd64.deb` and start `mpftp`. With
+  arguments, such as `mpftp --help` or `mpftp ls -d /dev/ttyACM0`, the same
+  command is the CLI, run with the Python the package carries.
 
 To serial ports on Linux, your user needs to be in the `dialout` group (or
 `uucp` on some distributions).

desktop/scripts/smoke_linux.sh

@@ -3,7 +3,8 @@
 # the window comes up on a virtual display, the app starts its Python host
 # and the sidecar with the Python it carries, and closing the app leaves no
 # Python behind. CI runs this on every build; it needs xvfb-run and, for a
-# .deb, sudo to install it.
+# .deb, sudo to install it. It also checks that `mpftp` with arguments is
+# the CLI, not the window.
 #
 #   smoke_linux.sh deb      path/to/mpftp_X.Y.Z_amd64.deb
 #   smoke_linux.sh appimage path/to/mpftp_X.Y.Z_amd64.AppImage
@@ -32,6 +33,16 @@ esac
 [[ -x "$python" ]] || { echo "::error::no bundled python3 in the $kind"; exit 1; }
 "$python" -I -c "import sys, mpftp.desktop_host, mpftp.sidecar; print(sys.version)"
 
+# With arguments the package's mpftp is the CLI: it prints and exits, and
+# no window or Python host starts.
+cli_out="$(timeout 60 "$app" --help 2>&1)" \
+  || { echo "::error::'mpftp --help' from the $kind failed"; echo "$cli_out"; exit 1; }
+grep -q '^usage: mpftp' <<<"$cli_out" \
+  || { echo "::error::'mpftp --help' from the $kind didn't print the CLI's help"; echo "$cli_out"; exit 1; }
+[[ -z "$(pgrep -f -- '-m mpftp.desktop_host' || true)" ]] \
+  || { echo "::error::'mpftp --help' from the $kind started the desktop host"; exit 1; }
+timeout 60 "$app" --version
+
 logs="$HOME/.local/share/com.pydevices.mpftp/logs"
 rm -rf "$logs"
 xvfb-run -a "$app" >"$work/app.out" 2>&1 &

desktop/src-tauri/src/main.rs

@@ -579,7 +579,52 @@ fn supervise(app: AppHandle, host: Arc<Host>, emu: Arc<Emu>, python: PathBuf, lo
     }
 }
 
+/// On Linux the package puts this app on PATH as `mpftp`, the CLI's own
+/// name. Started with arguments (`mpftp --help`, `mpftp ls -d ...`) it is the
+/// CLI: it runs the bundled Python's mpftp in its place and never opens a
+/// window. With none, from the launcher or a bare `mpftp`, it is the app.
+#[cfg(unix)]
+fn run_cli_if_asked() {
+    use std::os::unix::process::CommandExt;
+
+    let args: Vec<std::ffi::OsString> = std::env::args_os().skip(1).collect();
+    if args.is_empty() {
+        return;
+    }
+    let python = std::env::var_os("MPFTP_DESKTOP_PYTHON")
+        .map(PathBuf::from)
+        .or_else(|| {
+            let exe = std::env::current_exe().ok()?.canonicalize().ok()?;
+            let dir = exe.parent()?;
+            // Installed: /usr/bin/mpftp with its files in /usr/lib/mpftp
+            // (an AppImage keeps the same layout). A dev build keeps them
+            // beside the binary.
+            [
+                dir.join("../lib/mpftp/python/bin/python3"),
+                dir.join("python/bin/python3"),
+            ]
+            .into_iter()
+            .find(|p| p.is_file())
+        });
+    let Some(python) = python else {
+        eprintln!("mpftp: can't find the bundled Python, so the command line isn't available from this install");
+        std::process::exit(2);
+    };
+    let err = Command::new(&python)
+        .args(["-m", "mpftp"])
+        .args(&args)
+        // The CLI starts its sidecar with this same Python.
+        .env("MPFTP_PYTHON", &python)
+        .env("PYTHONNOUSERSITE", "1")
+        .exec();
+    eprintln!("mpftp: could not run {}: {err}", python.display());
+    std::process::exit(2);
+}
+
 fn main() {
+    #[cfg(unix)]
+    run_cli_if_asked();
+
     let host = Arc::new(Host::default());
     let host_for_exit = host.clone();
     let emu = Arc::new(Emu::default());