Update CAR INSTALL.md

diff --git a/CAR INSTALL.md b/CAR INSTALL.md
index 71da6f5cf7f539fa6f0e39717aad8b479a59ea0b..8d67cbd888fe79eeefdc86bad12d340e64ef4057 100644 (file)
--- a/CAR INSTALL.md
+++ b/CAR INSTALL.md
@@ -219,13 +219,14 @@ When the power source is switched on, typically when you start the car, it will
 ### Enjoy!
 
 ## Updating
-From time to time, you may wish to update this installation. When it comes to updating, you should undo the last few steps above to allow the device to reconnect to the network it was created on. 
-1. First, if it's a Raspberry Pi and you have enabled the Read-only mode, you must take the device out of Read-only mode. Then you can update it in the normal way. Here is how to take it out of Read-only mode:
+From time to time, you may wish to update this installation. However, in order to update Shairport Sync, you must reconnect the system to a network that can access the internet. The easiest thing is to temporarily reconnect to the network you used when you created the system. To do that, you have to temporarily undo the "Final Steps" and any of the "Raspberry Pi Specific" steps you used. This will enable you to connect your device back to the network it was created on. You should then be able to update the operating system and libraries in the normal way and then update Shairport Sync. So, take the following steps:
+
+1. If it's a Raspberry Pi and you have enabled the Read-only mode, you must take the device out of Read-only mode:
 
 Run `sudo raspi-config` and then choose `Performance Options` > `Overlay Filesystem` and choose to disable the overlay filesystem and to set the boot partition not to be write-protected. This is to enable changes to be made. Save the changes and reboot the system.
 
 
-2. Next, if you have disabled the `dhcpcd` and `wpa_supplicant` services as suggested above, you need to re-enable them:
+2. If you have disabled the `dhcpcd`, `wpa_supplicant` or `systemd-timesyncd` services as suggested in the "Optimise startup time -- Raspberry Pi Specific" section, you need to re-enable them:
 ```
 sudo systemctl enable dhcpcd.service
 sudo systemctl enable wpa_supplicant.service
@@ -233,7 +234,7 @@ sudo systemctl enable systemd-timesyncd.service
 ``` 
 Reboot.
 
-3. Next, to allow your device to connect to reconnect to the network it was created on, edit `/etc/dhcpcd.conf` and comment out the following line at the start:
+3. To allow your device to connect to reconnect to the network it was created on, edit `/etc/dhcpcd.conf` and comment out the following line at the start:
 ```
 denyinterfaces wlan0
 ```
@@ -241,17 +242,17 @@ so that it looks like this:
 ```
 # denyinterfaces wlan0
 ```
-From this point on, at least on the Raspberry Pi, if you reboot the machine, it will connect to the network it was configured on, i.e. the network you used when you set it up for the first time.
+From this point on, if you reboot the machine, it will connect to the network it was configured on, i.e. the network you used when you set it up for the first time. This is because the name and password of the network it was created on would have been placed in `/etc/wpa_supplicant/wpa_supplicant` when the system was initially configured and will still be there.
 
-You can perform updates in the normal way. When you are finished, you need to undo the temporary changes you made to the setup, as follows:
+You can perform updates in the normal way -- see [UPDATING](https://github.com/mikebrady/shairport-sync/blob/master/UPDATING.md). When you are finished, you need to undo the temporary changes you made to the setup, as follows:
 
-1. Disable the three system services you temporarily re-enabled:
+1. If you had temporarily re-enabled services that are normally disabled, then it's time to disable them again:
 ```
 sudo systemctl disable dhcpcd.service
 sudo systemctl disable wpa_supplicant.service
 sudo systemctl disable systemd-timesyncd.service
 ```
-2. Edit `/etc/dhcpcd.conf` and uncomment the following line that you had temporarily commented out at the start:
+2. To re-enable the system to create its own network, edit `/etc/dhcpcd.conf` and uncomment the line that you had temporarily commented out at the start of the update. Change:
 ```
 # denyinterfaces wlan0
 ```
@@ -259,6 +260,6 @@ so that it looks like this:
 ```
 denyinterfaces wlan0
 ```
-3. Reboot. The system should start, creating the WiFi network as it would if it was in the car. It remains now to make the file-system read-only, if desired.
-4. Connect to the system. Run `sudo raspi-config` and then choose `Performance Options` > `Overlay Filesystem` and choose to enable the overlay filesystem, and to set the boot partition to be write-protected.
-5. Do a final reboot and check that everyting is in order.
+3. Reboot. The system should start as it would if it was in the car.
+
+4. If the device is a Raspberry Pi and you wish to make the file system read-only, connect to the system, run `sudo raspi-config` and then choose `Performance Options` > `Overlay Filesystem`. In there, choose to enable the overlay filesystem, and to set the boot partition to be write-protected. Do a final reboot and check that everyting is in order.