fix(linux): add service mode installation for non-Debian distros

On Arch Linux and other non-Debian distros, the systemd service could
not be installed because: is_installed_daemon() returned true
unconditionally on Linux, no install card was shown in the Flutter UI,
and install_service() assumed the unit file was already in systemd's
search path.

Add is_installed_daemon() for Linux that checks /etc/systemd/system/
and /usr/lib/systemd/system/ for the unit file, and can install it via
GTK sudo dialog when prompted. Show an install card on the home page
(matching macOS behavior) when the daemon is not installed. Update
install_service() and uninstall_service() to handle unit file
copy/removal.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

flutter/lib/desktop/pages/desktop_home_page.dart

@@ -48,6 +48,7 @@ class _DesktopHomePageState extends State<DesktopHomePage>
   var watchIsProcessTrust = false;
   var watchIsInputMonitoring = false;
   var watchIsCanRecordAudio = false;
+  var watchIsInstalledDaemon = false;
   Timer? _updateTimer;
   bool isCardClosed = false;
 
@@ -518,6 +519,14 @@ class _DesktopHomePageState extends State<DesktopHomePage>
         return Container();
       }
       final LinuxCards = <Widget>[];
+      if (bind.mainIsInstalled() &&
+          !bind.mainIsInstalledDaemon(prompt: false)) {
+        LinuxCards.add(buildInstallCard(
+            "", "install_daemon_tip", "Install", () async {
+          bind.mainIsInstalledDaemon(prompt: true);
+          watchIsInstalledDaemon = true;
+        }, marginTop: LinuxCards.isEmpty ? 20.0 : 5.0));
+      }
       if (bind.isSelinuxEnforcing()) {
         // Check is SELinux enforcing, but show user a tip of is SELinux enabled for simple.
         final keyShowSelinuxHelpTip = "show-selinux-help-tip";
@@ -731,6 +740,12 @@ class _DesktopHomePageState extends State<DesktopHomePage>
           setState(() {});
         }
       }
+      if (watchIsInstalledDaemon) {
+        if (bind.mainIsInstalledDaemon(prompt: false)) {
+          watchIsInstalledDaemon = false;
+          setState(() {});
+        }
+      }
       if (watchIsCanRecordAudio) {
         if (isMacOS) {
           Future.microtask(() async {

src/platform/linux.rs

@@ -1948,6 +1948,69 @@ pub fn run_cmds_privileged(cmds: &str) -> bool {
     crate::platform::gtk_sudo::run(vec![cmds]).is_ok()
 }
 
+/// Check whether the systemd service unit file is installed, or trigger installation.
+///
+/// - `prompt=false`: Returns `true` if the unit file exists in systemd's search paths.
+/// - `prompt=true`: Spawns a background thread that copies the unit file into
+///   `/etc/systemd/system/`, reloads systemd, enables and starts the service.
+///   Always returns `false` immediately (async, mirrors macOS behavior).
+pub fn is_installed_daemon(prompt: bool) -> bool {
+    let app_name = crate::get_app_name().to_lowercase();
+    let unit_name = format!("{app_name}.service");
+
+    if !prompt {
+        return std::path::Path::new(&format!("/etc/systemd/system/{unit_name}")).exists()
+            || std::path::Path::new(&format!("/usr/lib/systemd/system/{unit_name}")).exists();
+    }
+
+    // prompt=true: install the unit file in a background thread
+    std::thread::spawn(move || {
+        if let Err(e) = install_systemd_unit(&app_name, &unit_name) {
+            log::error!("Failed to install systemd unit: {}", e);
+        }
+    });
+    false
+}
+
+/// Copy the systemd unit file to `/etc/systemd/system/`, reload, enable, and start.
+fn install_systemd_unit(app_name: &str, unit_name: &str) -> ResultType<()> {
+    // Try to read the unit file from the package-installed path first
+    let pkg_path = format!("/usr/share/{app_name}/files/systemd/{unit_name}");
+    let unit_contents = if std::path::Path::new(&pkg_path).exists() {
+        std::fs::read_to_string(&pkg_path)?
+    } else {
+        // Fall back to the embedded copy
+        include_str!("../../res/rustdesk.service").to_string()
+    };
+
+    // Fix pkill path to be absolute if /usr/bin/pkill exists
+    let unit_contents = if std::path::Path::new("/usr/bin/pkill").exists() {
+        unit_contents.replace("ExecStop=pkill ", "ExecStop=/usr/bin/pkill ")
+    } else {
+        unit_contents
+    };
+
+    // Write to a temp file, then use privileged copy
+    let tmp_path = format!("/tmp/.{unit_name}.tmp");
+    std::fs::write(&tmp_path, &unit_contents)?;
+
+    let dst = format!("/etc/systemd/system/{unit_name}");
+    let tmp_quoted = shell_quote(&tmp_path);
+    let dst_quoted = shell_quote(&dst);
+
+    let success = run_cmds_privileged(&format!(
+        "cp -f {tmp_quoted} {dst_quoted}; rm -f {tmp_quoted}; systemctl daemon-reload; systemctl enable {app_name}; systemctl start {app_name};"
+    ));
+
+    // Clean up temp file in case privileged command failed before removing it
+    std::fs::remove_file(&tmp_path).ok();
+
+    if !success {
+        bail!("Privileged command failed or was cancelled");
+    }
+    Ok(())
+}
+
 /// Spawn the current executable after a delay.
 ///
 /// # Security
@@ -2012,9 +2075,17 @@ pub fn uninstall_service(show_new_window: bool, _: bool) -> bool {
     log::info!("Uninstalling service...");
     let cp = switch_service(true);
     let app_name = crate::get_app_name().to_lowercase();
+    let unit_file = format!("/etc/systemd/system/{app_name}.service");
+    // Remove admin-installed unit file (not package-owned /usr/lib/systemd/system/)
+    let rm_unit = if std::path::Path::new(&unit_file).exists() {
+        let quoted = shell_quote(&unit_file);
+        format!("rm -f {quoted}; systemctl daemon-reload;")
+    } else {
+        String::new()
+    };
     // systemctl kill rustdesk --tray, execute cp first
     if !run_cmds_privileged(&format!(
-        "{cp} systemctl disable {app_name}; systemctl stop {app_name};"
+        "{cp} systemctl disable {app_name}; systemctl stop {app_name}; {rm_unit}"
     )) {
         Config::set_option("stop-service".into(), "".into());
         return true;
@@ -2034,7 +2105,15 @@ pub fn install_service() -> bool {
     log::info!("Installing service...");
     let cp = switch_service(false);
     let app_name = crate::get_app_name().to_lowercase();
-    if !run_cmds_privileged(&format!(
+    // If the unit file isn't installed yet, install it first
+    if !is_installed_daemon(false) {
+        let unit_name = format!("{app_name}.service");
+        if let Err(e) = install_systemd_unit(&app_name, &unit_name) {
+            log::error!("Failed to install systemd unit during service install: {}", e);
+            Config::set_option("stop-service".into(), "Y".into());
+            return true;
+        }
+    } else if !run_cmds_privileged(&format!(
         "{cp} systemctl enable {app_name}; systemctl start {app_name};"
     )) {
         Config::set_option("stop-service".into(), "Y".into());

src/ui_interface.rs

@@ -697,7 +697,9 @@ pub fn is_can_screen_recording(_prompt: bool) -> bool {
 pub fn is_installed_daemon(_prompt: bool) -> bool {
     #[cfg(target_os = "macos")]
     return crate::platform::macos::is_installed_daemon(_prompt);
-    #[cfg(not(target_os = "macos"))]
+    #[cfg(target_os = "linux")]
+    return crate::platform::linux::is_installed_daemon(_prompt);
+    #[cfg(not(any(target_os = "macos", target_os = "linux")))]
     return true;
 }