Use dexter for permissions

// Android Studio 4.0
android {
    buildFeatures {
        viewBinding = true
    }
}

class ContactsAdapter (private val mContacts: List<Contact>) : RecyclerView.Adapter<ContactsAdapter.ViewHolder>()
{
    // Provide a direct reference to each of the views within a data item
    // Used to cache the views within the item layout for fast access
    inner class ViewHolder(listItemView: View) : RecyclerView.ViewHolder(listItemView) {
        // Your holder should contain and initialize a member variable
        // for any view that will be set as you render a row
        val nameTextView = itemView.findViewById<TextView>(R.id.contact_name)
        val messageButton = itemView.findViewById<Button>(R.id.message_button)
    }

    // ... constructor and member variables
    // Usually involves inflating a layout from XML and returning the holder
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ContactsAdapter.ViewHolder {
        val context = parent.context
        val inflater = LayoutInflater.from(context)
        // Inflate the custom layout
        val contactView = inflater.inflate(R.layout.item_contact, parent, false)
        // Return a new holder instance
        return ViewHolder(contactView)
    }

    // Involves populating data into the item through holder
    override fun onBindViewHolder(viewHolder: ContactsAdapter.ViewHolder, position: Int) { 
        // Get the data model based on position
        val contact: Contact = mContacts.get(position)
        // Set item views based on your views and data model
        val textView = viewHolder.nameTextView
        textView.setText(contact.name)
        val button = viewHolder.messageButton
        button.text = if (contact.isOnline) "Message" else "Offline"
        button.isEnabled = contact.isOnline
    }

    // Returns the total count of items in the list
    override fun getItemCount(): Int {
        return mContacts.size
    }
}

<com.google.android.material.textfield.TextInputLayout
                android:id="@+id/til_title"
                style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent">

                <androidx.appcompat.widget.AppCompatEditText
                    android:id="@+id/et_title"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:hint="@string/edit_text_hint_title"
                    android:inputType="textCapWords"
                    android:textColor="@color/primaryTextColor"
                    android:textColorHint="@color/secondaryTextColor"
                    android:textSize="@dimen/edit_text_text_size" />
            </com.google.android.material.textfield.TextInputLayout>

try {
  	//open application settings
  	val intent = Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS)
  	val uri = Uri.fromParts("package",packageName, null)
  	intent.data = uri
  	startActivity(intent)
}catch (e:IOException){
  	e.printStackTrace()
}

private fun askPermissions(){
        Dexter.withContext(this)
                .withPermissions(
                        Manifest.permission.ACCESS_FINE_LOCATION,
                        Manifest.permission.ACCESS_COARSE_LOCATION
                )
                .withListener(object : MultiplePermissionsListener {
                    override fun onPermissionsChecked(report: MultiplePermissionsReport?) {
                        if (report!!.areAllPermissionsGranted()) {
                            // TODO (STEP 7: Call the location request function here.)
                        }

                        if (report.isAnyPermissionPermanentlyDenied) {
                            Toast.makeText(
                                    this@MainActivity,
                                    "You have denied location permission. Please allow it is mandatory.",
                                    Toast.LENGTH_SHORT
                            ).show()
                        }
                    }

                    override fun onPermissionRationaleShouldBeShown(
                            permissions: MutableList<PermissionRequest>?,
                            token: PermissionToken?
                    ) {
                        showRationalDialogForPermissions()
                    }
                }).onSameThread()
                .check()

    }

/etc/apt/sources.list.d

//MARK: - Location


 var locationManager = CLLocationManager()
    var currentLatitude = ""
    var currentLongitude = ""
    var cityName = ""
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        locationManager.delegate = self
        
        getLocation()
    }

extension LocationViewController: CLLocationManagerDelegate {
    
    func navigateToMaps() {
        
        let address = bookingModel.addressModel
        let lat = address["locationLat"] as? String ?? ""
        let longitude = address["locationLng"] as? String ?? ""
        //let title = address["location"] as? String ?? ""
        
        let destinationLatitude = Double(longitude) ?? 0.0 // Replace with the destination latitude
        let destinationLongitude: Double = Double(lat) ?? 0.0 // Replace with the destination longitude
        
        if UIApplication.shared.canOpenURL(URL(string: "http://maps.apple.com/")!) {
            // Open Apple Maps with the specified source and destination coordinates
            let mapsURL = URL(string: "http://maps.apple.com/?saddr=\(Double(currentLatitude) ?? 0.0),\(Double(currentLongitude) ?? 0.0)&daddr=\(destinationLatitude),\(destinationLongitude)")!
            UIApplication.shared.open(mapsURL, options: [:], completionHandler: nil)
        } else {
            // Handle the case where Apple Maps app is not available
            print("Apple Maps is not available")
        }
    }
    
    func getLocation () {
        
        if #available(iOS 14.0, *) {
            switch locationManager.authorizationStatus {
            case .notDetermined:
                locationManager.requestWhenInUseAuthorization()
                locationManager.requestLocation()
                break
            case .authorizedWhenInUse :
                locationManager.requestWhenInUseAuthorization()
                locationManager.requestLocation()
                break
                
            default:
                print("status : ", locationManager.authorizationStatus)
                break
            }
        } else {
            print("Error894")
            // Fallback on earlier versions
        }
    }
    
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        print("Got Location Data")
        if let location = locations.last {
            let lat = String(location.coordinate.latitude)
            let lng = String(location.coordinate.longitude)
            
            print("Lat : ", lat)
            print("lng : ", lng)
            
            getAddressFromLatLon(pdblLatitude: String(location.coordinate.latitude), withLongitude: String(location.coordinate.longitude))
        } else {
            print("error 120")
        }
    }
    
    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
        print("Error121 : ", error)
    }
    
    func getAddressFromLatLon(pdblLatitude: String, withLongitude pdblLongitude: String) {
        // SVProgressHUD.show()
        var center : CLLocationCoordinate2D = CLLocationCoordinate2D()
        let lat: Double = Double("\(pdblLatitude)")!
        //21.228124
        
        let lon: Double = Double("\(pdblLongitude)")!
        //72.833770
        let ceo: CLGeocoder = CLGeocoder()
        center.latitude = lat
        center.longitude = lon
        
        let loc: CLLocation = CLLocation(latitude:center.latitude, longitude: center.longitude)
        
        ceo.reverseGeocodeLocation(loc, completionHandler:
                                    {(placemarks, error) in
            if (error != nil)
            {
                print("reverse geodcode fail: \(error!.localizedDescription)")
                SVProgressHUD.dismiss()
                return
            }
            let pm = placemarks! as [CLPlacemark]
            
            for p in pm {
                print(" p :: ", p)
            }
            
            if pm.count > 0 {
                let pm = placemarks![0]
                let cityName = pm.locality ?? ""
                let timeZone : String = pm.timeZone?.identifier ?? ""
                
                print("timeZone : ", timeZone)
                print("country : ",pm.country ?? "")
                print("city : ", cityName)
                print("locLat : ", pdblLatitude)
                print("locLng : ", pdblLongitude)
                self.currentLatitude = pdblLatitude
                self.currentLongitude = pdblLongitude
                self.cityName = cityName
                self.getBookingCoordinates()
            }
            SVProgressHUD.dismiss()
        })
    }
}

# Check if 'webmasters' group exist

cat /etc/group | grep webmasters

# Create 'webmasters' group

sudo addgroup webmasters

# Add users to 'webmasters' group

sudo usermod -a -G webmasters username

# Group assignment changes won't take effect
# until the users log out and back in.


# Change group owner of the directory to webmaster user

sudo chgrp -R webmasters /etc/nginx/
  
# Give write permission to the group

sudo chmod -R g+w /etc/nginx/
  
# Create file as different user

sudo -u username touch /etc/nginx/test.txt

# When using a number mask for permission representation there are only a few basic permissions

4: Read
2: Write
1: Execute

# Combined you get this table

+-----+---+--------------------------+
| rwx | 7 | Read, write and execute  |
| rw- | 6 | Read, write              |
| r-x | 5 | Read, and execute        |
| r-- | 4 | Read,                    |
| -wx | 3 | Write and execute        |
| -w- | 2 | Write                    |
| --x | 1 | Execute                  |
| --- | 0 | no permissions           |
+------------------------------------+
  
# The permissions for user, group and other are listet after each other when looking them up

+------------+------+-------+
| Permission | Octal| Field |
+------------+------+-------+
| rwx------  | 700  | User  |
| ---rwx---  | 070  | Group |
| ------rwx  | 007  | Other |
+------------+------+-------+
  
# This boils down to this
  
  +------------------------+-----------+
| chmod u=rwx,g=rwx,o=rx | chmod 775 | For world readable directories
|                        |           |   Members of group can change files
| chmod u=rwx,g=rx,o=    | chmod 750 | For group readable directories
|                        |           |   Members of group can change files
| chmod u=rwx,go=        | chmod 700 | For private direcories
+------------------------+-----------+

# Deal with sudo authentication errors on back up
# two write permissions errors on backup restore:
# 1. check chown and chmod of sudo 
# 2. sudo: /usr/bin/sudo must be owned by uid 0 
# 3. and have the setuid bit set

# 1. sudo ownership
chown root:root /usr/bin/sudo && chmod 4755 /usr/bin/sudo

# 2. UID ownership
grep root /etc/passwd
# the default root should be set to:
# root:x:0:0:root:/root:/bin/bash
# if not sudoedit as above.

# 3. setuid bit
# check /usr/bin for setuid bit errors (vs. clean normal installation of distro)
# (for debian 11) incorrect configuration includes su and sudo and 8 other executables
# Incorrect format is (compare first 4 permsissions) 
# -rwxr-xr-x 1 root root 179K Feb 27 2021 sudo
# correct format is 
# -rwsr-xr-x 1 root root 182600 Feb 27  2021 /usr/bin/sudo
# prefer pkexec to nake changes 
pkexec chmod a=rx,u+ws /usr/bin/sudo
pkexec chmod a=rx,u+ws /usr/bin/su
# compare vs. a unmodified fresh virtual install of your system
# in Debian 11 8 further files need modifying

# bonus. on your way out check permissing in  /usr/lib/sudo/ and compare with base install.

# In Crosh
# Ctrl + Alt + t
vmc start termina
 lxc launch ubuntu:18.04 owo
  lxc file pull owo/usr/bin/lxc /tmp/lxc
  lxc file push /tmp/lxc penguin/usr/local/bin/
  lxc delete owo -f
  lxc config set core.https_address :8443
  lxc config set core.trust_password "a'really,good;password:^)"

# in container terminal
  lxc remote add chronos $(ip route show | awk '{print $3}' | head -n 1)
  lxc remote set-default chronos

# have fun
lxc exec container_name -- bash