Debian 13: removing kernel left over after kernel upgrade

wifi and some device require compile in debian depend on kernel version. this documentation is intended as a small guide to tidy up your system.

list of ii and rc status of package

# uname -r
6.12.63+deb13-amd64
# dpkg -l | grep linux-image
rc  linux-image-6.1.0-33-amd64                         6.1.133-1                            amd64        Linux 6.1 for 64-bit PCs (signed)
rc  linux-image-6.1.0-34-amd64                         6.1.135-1                            amd64        Linux 6.1 for 64-bit PCs (signed)
rc  linux-image-6.1.0-37-amd64                         6.1.140-1                            amd64        Linux 6.1 for 64-bit PCs (signed)
rc  linux-image-6.1.0-9-amd64                          6.1.27-1                             amd64        Linux 6.1 for 64-bit PCs (signed)
rc  linux-image-6.12.38+deb13-amd64                    6.12.38-1                            amd64        Linux 6.12 for 64-bit PCs (signed)
rc  linux-image-6.12.38+deb13-amd64-unsigned           6.12.38-1                            amd64        Linux 6.12 for 64-bit PCs
rc  linux-image-6.12.41+deb13-amd64                    6.12.41-1                            amd64        Linux 6.12 for 64-bit PCs (signed)
rc  linux-image-6.12.41+deb13-amd64-unsigned           6.12.41-1                            amd64        Linux 6.12 for 64-bit PCs
rc  linux-image-6.12.43+deb13-amd64                    6.12.43-1                            amd64        Linux 6.12 for 64-bit PCs (signed)
rc  linux-image-6.12.43+deb13-amd64-unsigned           6.12.43-1                            amd64        Linux 6.12 for 64-bit PCs
rc  linux-image-6.12.48+deb13-amd64                    6.12.48-1                            amd64        Linux 6.12 for 64-bit PCs (signed)
rc  linux-image-6.12.48+deb13-amd64-unsigned           6.12.48-1                            amd64        Linux 6.12 for 64-bit PCs
rc  linux-image-6.12.57+deb13-amd64                    6.12.57-1                            amd64        Linux 6.12 for 64-bit PCs (signed)
ii  linux-image-6.12.57+deb13-amd64-unsigned           6.12.57-1                            amd64        Linux 6.12 for 64-bit PCs
ii  linux-image-6.12.63+deb13-amd64                    6.12.63-1                            amd64        Linux 6.12 for 64-bit PCs (signed)
ii  linux-image-amd64                                  6.12.63-1                            amd64        Linux for 64-bit PCs (meta-package)

Note about rc and ii 

• rc = package removed, but config files remain
• ii = desired state install and current state installed 

we can conclude these packages are not used anymore but still exist in our system:

1. rc linux-image-6.1.0-*
2. rc linux-image-6.12.38*
3. rc linux-image-6.12.41*
4. rc linux-image-6.12.43*
5. rc linux-image-6.12.48*

We can remove those packages which is kernel left over, using this command:

# dpkg -l | awk '/^rc  linux-image/ {print $2}' | xargs dpkg --purge
(Reading database ... 180811 files and directories currently installed.)
Purging configuration files for linux-image-6.1.0-33-amd64 (6.1.133-1) ...
Purging configuration files for linux-image-6.1.0-34-amd64 (6.1.135-1) ...
Purging configuration files for linux-image-6.1.0-37-amd64 (6.1.140-1) ...
Purging configuration files for linux-image-6.1.0-9-amd64 (6.1.27-1) ...
dpkg: warning: while removing linux-image-6.1.0-9-amd64, directory '/lib/modules' not empty so not removed
Purging configuration files for linux-image-6.12.38+deb13-amd64 (6.12.38-1) ...
Purging configuration files for linux-image-6.12.38+deb13-amd64-unsigned (6.12.38-1) ...
rmdir: failed to remove '/lib/modules/6.12.38+deb13-amd64': No such file or directory
Purging configuration files for linux-image-6.12.41+deb13-amd64 (6.12.41-1) ...
Purging configuration files for linux-image-6.12.41+deb13-amd64-unsigned (6.12.41-1) ...
rmdir: failed to remove '/lib/modules/6.12.41+deb13-amd64': No such file or directory
Purging configuration files for linux-image-6.12.43+deb13-amd64 (6.12.43-1) ...
Purging configuration files for linux-image-6.12.43+deb13-amd64-unsigned (6.12.43-1) ...
rmdir: failed to remove '/lib/modules/6.12.43+deb13-amd64': No such file or directory
Purging configuration files for linux-image-6.12.48+deb13-amd64 (6.12.48-1) ...
Purging configuration files for linux-image-6.12.48+deb13-amd64-unsigned (6.12.48-1) ...
rmdir: failed to remove '/lib/modules/6.12.48+deb13-amd64': No such file or directory
Purging configuration files for linux-image-6.12.57+deb13-amd64 (6.12.57-1) ...
I: /vmlinuz is now a symlink to boot/vmlinuz-6.12.63+deb13-amd64
I: /initrd.img is now a symlink to boot/initrd.img-6.12.63+deb13-amd64
rmdir: failed to remove '/lib/modules/6.12.57+deb13-amd64': Directory not empty

 

 

Debian 13: using unbound as DNS over https resolver in conjuction with NetworkManager and Systemd Resolved

Assume:

• NetworkManager and Systemd-Resolved already work 

Install unbound

# apt-get install unbound

Edit /etc/systemd/resolved.conf and set:

[Resolve]
DNS=127.0.0.1:5335
Domains=~.

Make sure this line in /etc/unbound/unbound.conf

...
include-toplevel: "/etc/unbound/unbound.conf.d/*.conf"
...

Create and edit /etc/unbound/unbound.conf.d/google-doh.conf

server:
    # Port 5335 is safer for laptops than 5353 (mDNS)
    port: 5335
    interface: 127.0.0.1
    access-control: 127.0.0.0/8 allow
    
    # Required for TLS verification
    tls-cert-bundle: "/etc/ssl/certs/ca-certificates.crt"
forward-zone:
name: "."
    # Using DoT (Port 853) instead of DoH (Port 443)
    forward-tls-upstream: yes
    forward-addr: 8.8.8.8@853#dns.google
    forward-addr: 8.8.4.4@853#dns.google

Enable unbound and restart all services

# systemctl enable unbound
# systemctl start unbound
# systemctl restart systemd-resolved
# systemctl restart NetworkManager

Test

# resolvectl query google.com
google.com: 172.253.118.138
            172.253.118.102
            172.253.118.101
            172.253.118.113
            172.253.118.139
            172.253.118.100
            2404:6800:4003:c11::8a
            2404:6800:4003:c11::71
            2404:6800:4003:c11::64
            2404:6800:4003:c11::8b


# resolvectl query duckduckgo.com
duckduckgo.com: 20.43.161.105

-- Information acquired via protocol DNS in 54.3ms.
-- Data is authenticated: no; Data was acquired via local or encrypted transport: no
-- Data from: network

Android java: write and delete file into folder creeated by application in Download pattern code

Target device Android 7 (API 24) to Android 16 (API 36)

AndroidManifest.xml permission 

     <uses-permission
        android:name="android.permission.READ_EXTERNAL_STORAGE"
        android:maxSdkVersion="32" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
        android:maxSdkVersion="28" />
    <!-- targeting api 13++ use media store -->
    <uses-permission android:name="android.permission.POST_NOTIFICATIONS"/>

To write contact (vcard) to folder com.dedetok.wredacontactbackup in folder Download

    final static String subFolder = "com.dedetok.wredacontactbackup"; // folder ref
    private static File backupFolder, backupFile; //


    private static boolean writeSingleVcf(Context context, Collection<VCard> vCards) {
        try {

            String date = new SimpleDateFormat("yyyyMMddHHmmSS", Locale.US).format(new Date());
            String fileName = date + ".vcf";


            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
                // ✅ API 29-36 (Android 10+): Use MediaStore (Scoped Storage)
                return MyWorker.writeMediaStore(context, fileName, vCards);
            } else {
                // ✅ API 24-28 (Android 7-9): Use traditional File API
                // ✅ API 29-36 (Android 10+): Use MediaStore (Scoped Storage)
                return MyWorker.writeLegacy(context, fileName, vCards);

            }
        } catch (Exception e) {
            //Log.e("dedetok",e.getMessage()); // debug
            return false;
        }
    }


    /*
     * write backup MediaStore
     */
    @RequiresApi(api = Build.VERSION_CODES.Q)
    private static boolean writeMediaStore (Context context, String fileName, Collection<VCard> vCards) throws IOException{
        ContentValues values = new ContentValues();
        //Log.e("dedetok", "writeMediaStore"); // debug
        values.put(MediaStore.MediaColumns.DISPLAY_NAME, fileName);
        values.put(MediaStore.MediaColumns.MIME_TYPE, "text/x-vcard");
        // Creates 'Download/YourSubFolder/' automatically
        values.put(MediaStore.MediaColumns.RELATIVE_PATH,
                Environment.DIRECTORY_DOWNLOADS + File.separator + subFolder);

        Uri uri = context.getContentResolver().insert(
                MediaStore.Downloads.EXTERNAL_CONTENT_URI, values);
        if (uri == null) return false;

        OutputStream os = context.getContentResolver().openOutputStream(uri);
        Ezvcard.write(vCards).version(VCardVersion.V3_0).go(os);
        return true;
    }

    /*
     * write backup in legacy mode
     */
    private static boolean writeLegacy(Context context, String fileName, Collection<VCard> vCards) throws IOException{
        // Setup Directory
        File downloads = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
        backupFolder = new File(downloads, MySharePreferences.PREF_NAME);
        // Create folder if missing
        if (!backupFolder.exists()) {
            boolean success = backupFolder.mkdirs();
            if (!success) {
                //Log.e("dedetok", "Failed to create folder. Check permissions!"); // debug
                return false;
            }
        }

        backupFile = new File(backupFolder, fileName);
        try (FileOutputStream fos = new FileOutputStream(backupFile)) {
            Ezvcard.write(vCards).version(VCardVersion.V3_0).go(fos);
        }

        //Log.d("dedetok", "File saved at: " + backupFolder.getName()); // debug

        // Tell Android to scan the file so it shows up in Windows/File Manager
        MediaScannerConnection.scanFile(
                context,
                new String[]{ backupFile.getAbsolutePath() },
                null,
                new MediaScannerConnection.OnScanCompletedListener() {
                    @Override
                    public void onScanCompleted(String path, Uri uri) {
                        //Log.e("dedetok", "Scanned: " + path);
                    }
                }
        );

        //Log.e("dedetok", "File created successfully "+backupFile.getName()); // debug
        return true;

    }

To delete file created by application from folder com.dedetok.wredacontactbackup in folder Download

    /*
     * delete File helper for android 7 yo 16
     */
    static private boolean deleteFile(Context context, File fileToDelete) {
        boolean returnValue = false;
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
            // Android 7–9
            if (fileToDelete.exists()) {
                returnValue = fileToDelete.delete();
                if (returnValue) {
                    // IMPORTANT: Tell the system the file is gone so Google Files updates
                    MediaScannerConnection.scanFile(context, new String[]{fileToDelete.getAbsolutePath()}, null, null);
                }
            }
        } else {
            // Android 10 to 16
            ContentResolver resolver = context.getContentResolver();
            Uri collection = MediaStore.Downloads.EXTERNAL_CONTENT_URI;

            // IMPORTANT: RELATIVE_PATH must end with a slash /
            String relativePath = Environment.DIRECTORY_DOWNLOADS + "/" + subFolder + "/";

            String selection = MediaStore.MediaColumns.DISPLAY_NAME + "=? AND " +
                    MediaStore.MediaColumns.RELATIVE_PATH + "=?";

            String[] selectionArgs = new String[]{
                    fileToDelete.getName(),
                    relativePath
            };

            int rows = 0;
            try {
                // Directly delete from MediaStore - this usually deletes the physical file too
                rows = resolver.delete(collection, selection, selectionArgs);
            } catch (Exception e) {
                //Log.e("dedetok", "MediaStore delete failed", e);
            }

            if (rows > 0) {
                returnValue = true;
            } else {
                // FALLBACK: Physical delete if MediaStore didn't find it
                if (fileToDelete.exists()) {
                    returnValue = fileToDelete.delete();
                    if (returnValue) {
                        // Sync the index
                        MediaScannerConnection.scanFile(context, new String[]{fileToDelete.getAbsolutePath()}, null, null);
                    }
                }
            }
        }
        return returnValue;
    }

 

Android java: OnBackPressedDispatcher pattern code

AndroidManifest.xml 

    <application
...
        android:enableOnBackInvokedCallback="true" 

Main Activity 

On main activity declare:

        // callback on back key pressed
        OnBackPressedCallback myBackPressedCallback = new OnBackPressedCallback(true) {
            @Override
            public void handleOnBackPressed() {

                FragmentManager fm = getSupportFragmentManager();

                // Pop fragment back stack if possible
                if (fm.getBackStackEntryCount() > 0) {
                    fm.popBackStack();
                    return;
                }

                // Log.e("dedetok", "handleOnBackPressed()"); //debug
                AlertDialog.Builder myAliertDialog = new AlertDialog.Builder(
                        MainActivity.this);
                myAliertDialog.setTitle(R.string.dialog_title).
                        setMessage(R.string.dialog_message).
                        setIcon(android.R.drawable.ic_dialog_alert).
                        setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialogInterface, int i) {
                                // finish() will execute onDestroy()
                                finish();
                            }
                        }).
                        setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialogInterface, int i) {
                                // do nothing
                            }
                        }).
                        show();
            }
        };

onCreate() in main activity

    ...
        // onbackkeypress
        // onBackPressed() deprecated -> OnBackPressedCallback & getOnBackPressedDispatcher()
        // dispatcher
        OnBackPressedDispatcher myOnbackPressedDispatcher = getOnBackPressedDispatcher();

        // add callback to dispatcher
        myOnbackPressedDispatcher.addCallback(this, myBackPressedCallback);
    ...

Fragment

To replace fragment in main activity

               Fragment helpFragment = new FragmentHelp();

                requireActivity()
                        .getSupportFragmentManager()
                        .beginTransaction()
                        .replace(R.id.fragment_container, helpFragment)
                        .addToBackStack("help")
                        .commit();

addToBackStack("help") is the way android system implement on back pressed

If you have button back on your fragment e.g helpFragment, you need to emulate OnBackPressedDispatcher

                requireActivity()
                        .getOnBackPressedDispatcher()
                        .onBackPressed();

Activity B

onCreate in activity B

    // Inside Activity B's onCreate
    getOnBackPressedDispatcher().addCallback(this, new OnBackPressedCallback(true) {
        @Override
        public void handleOnBackPressed() {
        // This runs when the physical back button OR 
        // the programmatic onBackPressed() is called.
        finish(); 
        }
    });

    // Inside your Button's onClick (Assuming it's in the Activity)
    buttonExit.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
        // This triggers the callback above
        getOnBackPressedDispatcher().onBackPressed();
        }
    });

 

 

Privacy Policy for Wreda Contact Backup

 

Wreda Contact Backup

This application will help you to backup your contact offline. These application require permission:

1. Read Contact
2. Write Storage
3. Notification

No internet connection is require since the backup will store at Download folder with sub folder com.dedetok.wredacontactbackup folder. Maximum files are set to 60 to avoid fulling your phone get full.

Minimum Android supported is 7.0.

How to use

You can backup directly by pressing "Backup Now"

For Android supported you can make scheduled. The options are:

• Weekly
• Monthly

We don't provide cloud backup, you need to safe your backup file (vcf) manually in your trusted provider by uploading the vcf file.

Data Privacy Policy

The Application does not collect, store, or share any personal information from its users.

• No Personal Data: We do not collect names, email addresses, phone numbers, or physical addresses.
• No Device Identifiers: The application does not access your device's unique ID, IP address, or contacts.
• No Location Tracking: We do not track or collect real-time geographical location information.

The Application does not use third-party services (such as analytics or advertising SDKs) that collect data for identification or tracking.

Since the Application does not collect or store any user data, there is no risk of your personal data being accessed by unauthorized individuals through our servers.

If you have any questions or suggestions about this Privacy Policy, do not hesitate to contact us at dedetoke@gmail.com.