diff --git a/quickinstall b/quickinstall
index 41e4f8f0..4ec7f7ad 100755
--- a/quickinstall
+++ b/quickinstall
@@ -63,7 +63,6 @@ if [[ ! -d $BINDIR ]]; then
     echo "There is nothing to do."
     finish 0
 fi
-
 # Offer to install ckb at a standard location
 shopt -s nocasematch
 read -rp "Install ckb system-wide [Y/n]? " doinstall
@@ -191,8 +190,11 @@ sleep 1
 echo ""
 read -rp "Start ckb now [Y/n]? " dolaunch
 [[ $dolaunch =~ no? ]] && exit 0
-sleep 0.5
 APP=$PREFIX/ckb
 [[ "$OSTYPE" == "darwin"* ]] && APP=$APP.app/Contents/MacOS/ckb
+# Ask ckb to close if there's an instance already running
+$APP --close >/dev/null 2>&1
+sleep 0.5
+# Launch
 nohup $APP >/dev/null 2>&1 &
 exit 0
diff --git a/src/ckb/main.cpp b/src/ckb/main.cpp
index a064fdce..236505a0 100644
--- a/src/ckb/main.cpp
+++ b/src/ckb/main.cpp
@@ -3,6 +3,9 @@
 #include <QDateTime>
 #include <QSharedMemory>
 #include <cstring>
+#include <unistd.h>
+#include <signal.h>
+#include <errno.h>
 
 QSharedMemory appShare("ckb");
 
@@ -12,17 +15,64 @@ QSharedMemory appShare("ckb");
 extern "C" void disableAppNap();
 #endif
 
-bool isRunning(bool showWindow){
-    if(!appShare.create(16)){
-        if(!appShare.attach() || !appShare.lock())
-            return false;
-        if(showWindow){
-            void* data = appShare.data();
-            snprintf((char*)data, 16, "Open");
+// Shared memory sizes
+#define SHMEM_SIZE      128 * 1024
+#define SHMEM_SIZE_V015 16
+
+// Scan shared memory for an active PID
+static bool pidActive(const QStringList& lines){
+    foreach(const QString& line, lines){
+        if(line.startsWith("PID ")){
+            bool ok;
+            pid_t pid;
+            // Valid PID found?
+            if((pid = line.split(" ")[1].toLong(&ok)) > 0 && ok){
+                // kill -0 does nothing to the application, but checks if it's running
+                return (kill(pid, 0) == 0 || errno != ESRCH);
+            }
         }
-        appShare.unlock();
-        return true;
     }
+    // If the PID wasn't listed in the shmem, assume it is running
+    return true;
+}
+
+// Check if the application is running. Optionally write something to its shared memory.
+static bool isRunning(const char* command){
+    // Try to create shared memory (if successful, application was not already running)
+    if(!appShare.create(SHMEM_SIZE) || !appShare.lock()){
+        // Lock existing shared memory
+        if(!appShare.attach() || !appShare.lock())
+            return true;
+        bool running = false;
+        if(appShare.size() == SHMEM_SIZE_V015){
+            // Old shmem - no PID listed so assume the process is running, and print the command directly to the buffer
+            if(command){
+                void* data = appShare.data();
+                snprintf((char*)data, SHMEM_SIZE_V015, "%s", command);
+            }
+            running = true;
+        } else {
+            // New shmem. Scan the contents of the shared memory for a PID
+            QStringList lines = QString((const char*)appShare.constData()).split("\n");
+            if(pidActive(lines)){
+                running = true;
+                // Append the command
+                if(command){
+                    lines.append(QString("Option ") + command);
+                    QByteArray newMem = lines.join("\n").left(SHMEM_SIZE).toLatin1();
+                    // Copy the NUL byte as well as the string
+                    memcpy(appShare.data(), newMem.constData(), newMem.length() + 1);
+                }
+            }
+        }
+        if(running){
+            appShare.unlock();
+            return true;
+        }
+    }
+    // Not already running. Initialize the shared memory with our PID
+    snprintf((char*)appShare.data(), appShare.size(), "PID %ld", (long)getpid());
+    appShare.unlock();
     return false;
 }
 
@@ -40,8 +90,24 @@ int main(int argc, char *argv[]){
     qApp->setAttribute(Qt::AA_UseHighDpiPixmaps);
 #endif
 
+    // If launched with --version, print version info and then quit
+    if(qApp->arguments().contains("--version")){
+        printf("ckb %s\n", CKB_VERSION_STR);
+        return 0;
+    }
+
+    // Kill existing app when launched with --close
+    if(qApp->arguments().contains("--close")){
+        if(isRunning("Close"))
+            printf("Asking existing instance to close.\n");
+        else
+            printf("ckb is not running.\n");
+        return 0;
+    }
+
+    // Launch in background if requested
     bool background = qApp->arguments().contains("--background");
-    if(isRunning(!background)){
+    if(isRunning(background ? 0 : "Open")){
         printf("ckb is already running. Exiting.\n");
         return 0;
     }
diff --git a/src/ckb/mainwindow.cpp b/src/ckb/mainwindow.cpp
index e1bdeed5..6f1a0d8a 100644
--- a/src/ckb/mainwindow.cpp
+++ b/src/ckb/mainwindow.cpp
@@ -6,6 +6,7 @@
 #include <QShortcut>
 #include <QMessageBox>
 #include <QMenuBar>
+#include <unistd.h>
 
 extern QSharedMemory appShare;
 
@@ -204,14 +205,29 @@ void MainWindow::closeEvent(QCloseEvent *event){
 }
 
 void MainWindow::timerTick(){
-    // Check if another instance requested this in the foreground
+    // Check shared memory for changes
     if(appShare.lock()){
         void* data = appShare.data();
-        if((QString)QByteArray((const char*)data) == "Open")
-            showWindow();
-        // Remove the request
-        *(char*)data = 0;
+        QStringList commands = QString((const char*)data).split("\n");
+        // Restore PID, remove all other data
+        snprintf((char*)appShare.data(), appShare.size(), "PID %ld", (long)getpid());
         appShare.unlock();
+        // Parse commands
+        foreach(const QString& line, commands){
+            // Old ckb option line - bring application to foreground
+            if(line == "Open")
+                showWindow();
+            if(line.startsWith("Option ")){
+                // New ckb option line
+                QString option = line.split(" ")[1];
+                if(option == "Open")
+                    // Bring to foreground
+                    showWindow();
+                else if(option == "Close")
+                    // Quit application
+                    qApp->quit();
+            }
+        }
     }
     // Check for firmware updates (when appropriate)
     if(!CkbSettings::get("Program/DisableAutoFWCheck").toBool())