Rewrite debug docs (#142)

docs/debugging.md

@@ -1,15 +1,80 @@
 # Debugging
 
-When reporting a bug or posting questions to [issues](https://github.com/UniPiTechnology/evok/issues) please set logging levels in `/etc/evok/config.yaml` to `DEBUG`, restart Evok service and check the logs with command `journalctl -eu evok`. For more detailed log information you can also run Evok manually. In order to do that, you need to stop its service first.
+Debugging allows you to see what is done internally in Evok, in case you face any troubles.
+
+## Single start in debug mode
+
+If you wish to debug a single event and then run Evok in normal mode, you can launch Evok in debug mode.
+You need to stop the running Evok service first.
 
 ```bash title="Stopping Evok service"
-systemctl stop evok
+sudo systemctl stop evok
 ```
 
+Now, you can manually run Evok in debug mode, the output will be printed to the terminal.
+
 ```bash title="Running Evok manually"
 /opt/evok/bin/evok -d
 ```
 
+## Setting permanent debug mode
+
+If you need to debug an issue that occurs rarely, you can set Evok to run in debug mode permanently.
+You have to change `logging: level:` to `DEBUG` in `/etc/evok/config.yaml`.
+Use text editor of your choice, we recommend using `nano` (do `sudo apt install nano` if not present on your system).
+
+```bash title="Editing configuration file"
+sudo nano /etc/evok/config.yaml
+```
+
+Find this section:
+
+```yaml
+#   +------------------+
+#   | Logging settings |
+#   +------------------+
+logging:
+  level: WARNING
+  # ^ Minimum severity of messages to be logged, where minimum is CRITICAL.
+  # ^ Options: [CRITICAL, ERROR, WARNING, INFO, DEBUG]
+```
+
+And change the `level` value to `DEBUG`:
+
+```yaml
+#   +------------------+
+#   | Logging settings |
+#   +------------------+
+logging:
+  level: DEBUG
+  # ^ Minimum severity of messages to be logged, where minimum is CRITICAL.
+  # ^ Options: [CRITICAL, ERROR, WARNING, INFO, DEBUG]
+```
+
+Now, save via `CTRL+X`, then press `ENTER` and exit by `CTRL+X`.
+The Evok service has to be restarted now.
+
+```bash title="Restarting Evok service"
+sudo systemctl restart evok
+```
+
+### Reading the logs
+
+To read the logs from Evok in permanent debug mode, you can use following command. It also prints information about other related services.
+
+```bash title="Viewing the Evok log"
+journalctl -e -u evok
+```
+
+You can scroll in the outuput via arrow keys.
+If you wish to copy the output (no scrolling), use following command:
+
+```bash title="Copying the Evok log"
+journalctl --no-pager -u evok -u unipi-one-modbus
+```
+
+This is more practical, as it's almost impossible to copy larger section of the log, when you have to scroll trough it.
+
 !!! success
 
     You can examine or copy the output.