I'm using LineageOS 14.1 and don't want nor need to root it. How can I remount
/system rw and edit
All answers in "How to edit 'etc/hosts' file?" expect a rooted phone.
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Unless I missed something, that is not possible. Without root access only the mechanism of flashing an update (via recovery or OTA) can modify
/system. To be accepted, such an update archive must be signed with the same key as the ROM – which is something only the developer of the ROM (here: the LOS team) can do.
There might be a way via a custom recovery which lets you edit all file systems directly (see e.g. twrp). But without knowing what device it is, it cannot be said if a matching recovery exists (you can check that in the Devices section of their website for official images, and search XDA for unofficial ones). Apart from that, it's either rooting the device or not editing any file within
It is possible to use a VPN profile* to affect hostname resolution. There are a number of apps now available on the Play Store that provide a convenient way to do this, such as Hosts Go. Note that, since this technique requires the use of a VPN profile, you won't be able to use an actual VPN in conjunction with this technique.
*As of Android 4.0 (API Level 14) — https://developer.android.com/guide/topics/connectivity/vpn
On non-rooted phone you cannot actually edit
hosts file but it's possible to use VPN apps like Virtual Hosts or Personal DNS Filter (both are open-source, I've no affiliation with either) which intercept DNS traffic and look up a custom
hosts file before making queries to configured upstream DNS server.
Or if bootloader is unlockable, editing
hosts file is possible through custom recovery.
For more alternatives see: How to always resolve a domain name to a fixed IP without rooting?
I've seen some comments saying TWRP isn't explained clearly. This way you will only need developer options enabled.
So first get the file in your computer
adb pull /system/etc/hosts hosts
Edit the pulled hosts and push it again to the phone into a folder you have write permissions
adb push hosts /sdcard
Reboot the phone into recovery mode (TWRP), then go to mount and check "system" (DON'T check the "Mount system partition read-only"), go back and advanced -> File manager. Now you have a file manager with the system partition writable. Rename /system/etc/hosts to something like hosts_old, then move you edited hosts file /sdcard/hosts to /system/etc .
Warning: this will work only if ADB can get root access, which isn't the case for most ROMs. It works in in LineageOS 14.1.
Developer optionsenabled in phone
adbinstalled in computer
Apply the following settings in
Android debugging-> on
Connect the phone to the computer. Grant permission in your phone if asked. In the computer, launch a terminal and run
$ adb root
Grant permission in your phone. Remount with
$ adb remount
Start a remote rooted shell
$ adb shell
In the adb shell, edit your hosts file
# nano /etc/hosts
When ready, disconnect