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I'm using LineageOS 14.1 and don't want nor need to root it. How can I remount /system rw and edit /system/etc/hosts?

All answers in "How to edit 'etc/hosts' file?" expect a rooted phone.

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9

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. ). 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 the device or not editing any file within /system.

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  • Thanks. twrp looks like a very good solution. It has everything needed for small manual changes or full hosts replacements. I'm running the latest stable which ships with BusyBox: vi, cat, chmod and chown are there. – berbt May 9 '17 at 23:19
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    What is more, you don't have to install it – you can simply boot the image (fastboot boot twrp.img). Which leaves unlocking the bootloader as the only device modification (otside the one you just want to perform, of course ;) – Izzy♦ May 10 '17 at 6:55
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    My steps to modify it using TWRP: 0. boot into recovery 1. mount system 2. Advanced> File manager > navigate to file and click button "chmod 755" 2. advanced > terminal > vi /system/etc/hosts 3. make your changes (5. ESC, :wq to save and exit vi) – karfau Aug 31 '20 at 14:00
  • @karfau your comment could be turned into an Answer – Henrique de Sousa Oct 28 '20 at 1:03
  • @karfau your TWRP steps from the Mount System to the Advanced FIle Manager are not clear - I mount the system but it doesn't go anywhere - returns me back to the same option list (I downloaded the twrp img for the device). It would be helpful if you expanded on your method some more here - Please, pretty please? – Martin Sansone - MiOEE Nov 16 '20 at 2:43
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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

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    The Hosts Go app does work to add a few hosts entries. The documentation could be a lot better though. You can tell the author is not a native English speaker. In short you need to: run the app, add extra hosts entries, turn on "host change switch" and then click the big start button. That starts host name resolution. You should be able to use those hosts in chrome now, for example. The stop button take you back to normal host name resultion – Gary Nov 20 '19 at 2:48
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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?

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  • It seems that Personal DNS Filter doesn't allow for setting custom name resolution: it can only block names. – L. Levrel Nov 17 '20 at 10:32
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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.

Requirements:

  • Developer options enabled in phone
  • adb installed in computer

Steps

Apply the following settings in Developer options:

  • Root access -> ADB only
  • 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

# exit
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    Huh? On LOS root is only available if you flash the additional root package, which OP doesn't want to (i.e. "Root access = ADB only" cannot be achieved). So how should your steps work without root if they require root? Could you please clarify? – Izzy♦ May 9 '17 at 12:46
  • adbd cannot run as root in production build. – iBug May 9 '17 at 13:18
  • Also, how can you get nano? cat is all that you've got. Android does not even ship with a basic vi. – iBug May 9 '17 at 13:19
  • @Izzy just borrowed a phone with stock Android to confirm and yes, it seems to be a LOS thing. I didn't flash the root package. I'll modify my answer and the question title to reflect this fact. – berbt May 9 '17 at 13:43
  • @iBug same as my previous comment: most likely a LOS thing. nano is in /system/xbin/nano. vim--version (in /system/xbin/ too, no vi alias) says it was "Compiled by tpruvot@CyanogenMod". – berbt May 9 '17 at 13:55

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