Do you have an old Android phone laying around which has not received any official updates for a long time? Or you might be concerned about Google tracking your device and collecting tons of data about you and want to try open source android without bloatware and trackers? Or maybe you would like to try privacy oriented OS on your mobile phone?
These are just a few examples on why would you want to install Lineage OS on your phone. Just a quick note, that there are several options available for you if you are looking to improve your privacy. If you own a Google Pixel device, I would recommend to take a look at GrapheneOS. Being a great option, unfortunately at the time of the writing GrapheneOS does not support any other devices than Google phones. There is also CalyxOS that supports Google phones + a couple of other models, but their support is also very limited. OnePlus 8T and 9 models are due to be supported in December 2024 at the time of writing this post.
So if you are not a lucky owner of Google phone, than LineageOS is a good choice for a privacy oriented OS. If you plan to use applications from the Google Play store (downloaded as .apk or via Aurora Store for example), than a good option is to install microG as well. There is also a pre-configured LineageOS that includes a microG package as well as F-Droid, that you can use for downloading open source applications from.
In my example I will be using OnePlus 5 phone and official instructions from LineageOS website. Please search for your phone model on the website as there might be some differences.
You will need an adb and fastboot (sudo apt-get install adb fastboot if you are on Linux). First you will need to enable developers mode (search for how is it done on your device), then enable the USB debugging from the developer’s menu of your phone and connect it via the USB cable to your computer.
adb reboot bootloader
Will boot your device to bootloader mode.
Next, issue a command:
fastboot oem unlock
Note, if you will get an error (remote: 'Flashing Unlock is not allowed'), make sure that you have allowed unlocking bootloader in the developer’s menu.
Your device will reboot and you will need to re-enable the USB debugging from the developer’s menu again and boot to bootloader to flash your recovery image:
fastboot flash recovery <img_file>.img
Use your phone buttons to find and choose an option to boot to recovery. Do a Factory reset then Format data/factory reset. This will erase all the contents of your phone.
Next from the main menu tap on Apply update followed by Apply from ADB. On your computer type:
adb sideload <name_of_lineage_package>.zip
If you want to install additional packages such as Google Apps or Magisk (for rooting your phone), you can repeat the adb sideload process.
When you are ready you can reboot your system and you’re all done!