Database Develop

mount second sd card as a directory so car detects music over USB

Hi,
I use my telephone with a second sd card in the car through usb.
Appearently the car only finds and indexes the first sd card.
Is there a way to mount the sceond card as a directory on the first card?
Kind Regards
Guy F
I found a file vold.fstab in my /etc/system but there's no info regarding the second sd card?
Can I safely edit and how?
# Vold 2.0 Generic fstab
## - San Mehat ([email protected])
##
#######################
## Regular device mount
##
## Format: dev_mount <label> <mount_point> <part> <sysfs_path1...>
## label - Label for the volume
## mount_point - Where the volume will be mounted
## part - Partition # (1 based), or 'auto' for first usable partition.
## <sysfs_path> - List of sysfs paths to source devices
######################
#FIXME: Swap again?
# internal sdcard
dev_mount emmc /storage/sdcard1 auto /devices/platform/s3c-sdhci.2/mmc_host/mmc2
# external sdcard
dev_mount sdcard /storage/sdcard0 1 /devices/platform/s3c-sdhci.0/mmc_host/mmc0

I have looked here
http://forum.xda-developers.com/showthread.php?t=1922272
http://forum.xda-developers.com/showthread.php?t=1724287
http://forum.xda-developers.com/showthread.php?t=1785245
but I can't seem to get it to work
Anybody?

Forssound said:
I have looked here
http://forum.xda-developers.com/showthread.php?t=1922272
http://forum.xda-developers.com/showthread.php?t=1724287
http://forum.xda-developers.com/showthread.php?t=1785245
but I can't seem to get it to work
Anybody?
Click to expand...
Click to collapse
It seems I found a solution here http://forum.xda-developers.com/showthread.php?t=1511619
In brief
install a app like SSHDroid
on your desktop connect with putty to your phone so hook up your phone with the usb cable
login is or was "root" and password is "admin"
ls /dev/block/vold will give you some figures 179.0 179.2 179.2 179.8 179.9
ls /dev/block/platform will give some folders s3c-sdchi.0 s3c-sdchi.2 s5pc110-onenand
One can chose between several ways how the folders appear on a windows explorer folder
like a USB stick or a mediaplayer
setprop persist.sys.usb.config mtp,adb results in the little walkman icon on your explorer
setprop persist.sys.usb.config mass_storage,adb results in the appearing of a usb stick
mount is also a commando when given alone which will show you everything that is mounted
In the putty window i did a feel free to experiment
setprop persist.sys.usb.config mass_storage,adb
echo /dev/block/vold/179:9 > /sys/devices/platform/s3c-usbgadget/gadget/lun1/file"
This would result in the appearing of a USB stick with name sdcard on your file explorer in windows.
To make this flash persistent
Look if your rom has support for userinit.d or bootcompletehook.sh somewhere in /data
cm 10.1 has support for userinit.d
in /system/etc/init.d I found 2 files 00banner and 90userinit
vi /system/etc/init.d/90userinit is this
#!/system/bin/sh
# call userinit.sh and/or userinit.d/* scripts if present in /data/local
if [ -e /data/local/userinit.sh ];
then
log -p i -t userinit "Executing /data/local/userinit.sh";
logwrapper /system/bin/sh /data/local/userinit.sh;
setprop cm.userinit.active 1;
fi;
if [ -d /data/local/userinit.d ];
then
logwrapper busybox run-parts /data/local/userinit.d;
setprop cm.userinit.active 1;
fi;
now the folder wasn't there so
mkdir /data/local/userinit.d
in this folder make a file.The name isn't important
cd /data/local/userinit.d
vi mountsdcard
setprop persist.sys.usb.config mass_storage,adb
echo /dev/block/vold/179:9 > /sys/devices/platform/s3c-usbgadget/gadget/lun1/file
make sure you give rights to this file and the folder one can do that with es file explorer or probable
chmod 751 mountsdcard
I think that's it
This will mount your second sdcard (if you have one ) on your windows like a usb stick. It will do this even if your phone isn't completely started up.
You will not have to do a "mount usb" on your phone. If you do this anyway your first card is also mounted.
This is a neat trick to make your CAR find your music on your phone. If your car has a usb port and the functionality to play music from usb sticks.
Kind Regards
Guy

I tried doing the same by bind-mounting the external_sd on a folder on the internal_sd:
Code:
mount -o bind /storage/sdcard1 /storage/sdcard0/external_sd/
In the terminal it worked like a charm, but i couldn't get it to work at boot. Have you any other ideas?

Wouldn't it be easier to just mount the ext SD to a folder on the internal SD? This seems like 100 times the work really needed.
I can't recall atm how mounting of SD cards works, but if I had this problem I'd probably just put the songs in a .img file and mount that with
mount -o loop -t auto /storage/sdcard1/music.img /storage/sdcard2/music/
Sent from my GT-I9000 using xda premium

Yeah thats kinda what i thought of. But my init script is not getting executed or at least there is no effect of it.

I assume you've tested it with terminal output, what doesn't work about it? :/
Sent from my GT-I9000 using xda premium

I don't know what you mean, to be honest. I know that init.d should write the logs somewhere but couldn't find out where they are written to.
Edit: when i try to execute the command above it works, but it doesn't work with init.d

wget21 said:
I tried doing the same by bind-mounting the external_sd on a folder on the internal_sd:
Code:
mount -o bind /storage/sdcard1 /storage/sdcard0/external_sd/
In the terminal it worked like a charm, but i couldn't get it to work at boot. Have you any other ideas?
Click to expand...
Click to collapse
Read my large post..... It works on reboot and flash... I have tested it in my car and on my PC..

wget21 said:
I don't know what you mean, to be honest. I know that init.d should write the logs somewhere but couldn't find out where they are written to.
Edit: when i try to execute the command above it works, but it doesn't work with init.d
Click to expand...
Click to collapse
Well, for what it's worth you can use CM File Manager to add a shortcut on your home screen if you're on a ROM with Trebuchet Launcher, do that with the executable file and you can at least launch it easily when needed...
With pretty much any other launcher custom shortcuts are supported as is, Trebuchet for some reason lacks it.
(I loathe init.d)
Sent from my GT-I9000 using xda premium

I have now made a script in rom toolbox which does the job, but i'm not very happy with this. I'd prefer doing this simple bind-mount with init.d
@Forssound: Your solution seems to me a bit complicated, just for this simple task.

How To Guide How to change the home directory for the user root on an Android phone

How to change the home directory for the user root on an Android phone
When working a lot in a shell via adb on an Android phone it's usefull to be able to store some user dependent config files in the home directory of the user. So let's see how that can be implemented on a phone running Android.
Note: The config was done and tested on a phone running OmniROM (based on Android 12)
The home directory for all user used in an (adb) shell on Android is the root directory "/".
Using a home directory for more then one user is not really usefull and in addition on Android "/" is mounted read-only so more or less useless as home directory.
Therefor this should be changed . Unfortunately there is no /etc/passwd file in Android to configure the home directory for a user.
Well, there is an /etc/passwd file (probably for compatibily reasons) but it's empty:
Code:
[email protected]_I006D:/ $ ls -l /etc/passwd
-rw-r--r-- 1 root root 0 2009-01-01 01:00 /etc/passwd
[email protected]_I006D:/ $
And as far as I know there is no other config file to configure the home directory of the user in the Android OS.
So we must implement some work around to get this working.
The shell on Android behaves like normal shells on Linux and executes the file /etc/profile when starting a new session.
In Android /etc is a symbolic link to /system/etc:
Code:
[email protected]_I006D:/ # ls -ld /etc
lrw-r--r-- 1 root root 11 2009-01-01 01:00 /etc -> /system/etc
[email protected]_I006D:/ #
And in the default config there is no file called profile in that directory:
Code:
[email protected]_I006D:/ $ ls -l /etc/system/profile
ls: /etc/system/profile: No such file or directory
[email protected]_I006D:/ $
Because /system is also mounted read-only we need the magic tool Magisk again to create the file /system/etc/profile.
To create the file /system/etc/profile create these directories and files on the phone as user root (assuming Magisk is already installed on the phone):
Code:
[email protected]_I006D:/ # find /data/adb/modules/initshell/
/data/adb/modules/initshell/
/data/adb/modules/initshell/system
/data/adb/modules/initshell/system/etc
/data/adb/modules/initshell/system/etc/profile
[email protected]_I006D:/ #
and reboot the phone. After the reboot there should be the writable file /etc/profile:
Code:
[email protected]_I006D:/ # ls -l /etc/profile
-rw-rw-rw- 1 root root 1100 2022-07-14 14:51 /etc/profile
[email protected]_I006D:/ #
which is in reality the file
Code:
/data/adb/modules/initshell/system/etc/profile
Now you can edit the file /etc/profile as user root until it fullfills your requirements (be aware that all changes in that file are now persistent).
To test the changes open a new adb session (you should not close the current adb session to be able to fix an error in the profile if opening a new adb session fails).
This file can now be used to define the home directory for the user. The home directory should be on one of the writable filesystem, e.g. in /data:
Code:
# add in /etc/profile
HOME="/data/home/root"
export HOME
and the result is:
Code:
[email protected]_I006D:/ # id
uid=0(root) gid=0(root) groups=0(root),1004(input),1007(log),1011(adb),1015(sdcard_rw),1028(sdcard_r),1078(ext_data_rw),1079(ext_obb_rw),3001(net_bt_admin),3002(net_bt),3003(inet),3006(net_bw_stats),3009(readproc),3011(uhid) context=u:r:su:s0
[email protected]_I006D:/ # echo $HOME
/data/home/root
[email protected]_I006D:/ #
Note that there is not really a writable filesystem for the user shell so this approach to change the home directory is mainly usable for the user root.
The file /etc/profile can also be used to init some other settings for (adb) sessions (e..g. change the PATH, etc) . This feature can be used for sessions for non-root users also.
For additional user dependent configs you can also create the file .profile in the home directory of the user; the file ${HOME}/.profile will be executed after the execution of the file /etc/profile.
Notes:
Be aware that creating a profile for the user root and changing the home directory for the user root might have some side effects on other processes using the shell!
Therefor it's recommended to use the command "tty -s" to test if the profile is executed in an interactive session:
Code:
#
# check if we're running in an interactive session
#
if ! tty -s; then
#
# this is not an interactive session - so we're just doing nothing at all
#
:
else
#
# running in an interactive session
#
...
fi
You can also check if the parent process is the adb daemon to not do anything in non-adb sessions.
Code:
ps -fp $PPID| grep adbd >/dev/null
if [ $? -ne 0 ] ; then
#
# not running in an adb session
:
else
#
# running in an adb session
...
fi
For testing purpose I suggest to open at least two shells via adb to be able to fix an error in case opening a new shell fails due to a bug in the profile.
If opening a shell session fails due to an error in the /etc/profile and you do not have another open shell either delete the file /data/adb/modules/initshell/system/etc/profile with a filemanager with root access on the phone or boot the phone from a recovery image (like TWRP) and delete or edit the file /data/adb/modules/initshell/system/etc/profile.
I initially looked at this feature to enable a persistent command history for the shell on the Android phone. But after some google searches I found out that persistent history shells are disabled for the shell binary on Android. So this will not work without recompiling the shell binary.
The attached example for the profile (rename the attached file profile.txt to profile) will use the directory /data/home/root as home directory for the user root and will not change the home directory for other users. The profile will do nothing if not running in an interactive session.
The directory /data/home/root will be created by the profile if it does not yet exist.
As always, if the config is working you should create a real Magisk Module for the profile.
The Magisk Module attached, initshell.zip, can be used to create a Magisk Module with your own profile:
To create a new Magisk Module with your own /etc/profile do:
Code:
# create an empty working directory
#
TEMPDIR="/tmp/newdir"
mkdir "${TEMPDIR}"
cd "${TEMPDIR}"
# unpack the zip file in the new directory
#
unzip ../initshell.zip
# now edit the file ${TEMPDIR}/system/etc/profile
# also (optional) edit the files config.sh and module.prop in the new directory to document your changes
# the script customize.sh from the module will be executed once when the module is installed. You might add the code
# create the home directories or any other code here
#
# and recreate the zip file
#
zip -r ../initshell.zip .
Note:
Both attached files are also available from my web site: http://bnsmb.de/My_HowTos_for_Android.html

How To Guide How to create or change a swap device in the OmniROM using Magisk

How to create or change a swap device in the OmniROM using Magisk
The init script in the OmniROM running on the ASUS Zenfone 8 to create a swap device is:
/vendor/bin/init.asus.zram.sh
This script will create a swap device while booting the OS if that functionality is enabled.
To check if there is a swap device configured use the OS command free:
Code:
[email protected]_I006D:/ # free
total used free shared buffers
Mem: 7612493824 4732076032 2880417792 12857344 15298560
-/+ buffers/cache: 4716777472 2895716352
Swap: 4294963200 0 4294963200
[email protected]_I006D:/ #
If the result of the script is not okay you can create a Magisk script to correct the config for the swap device.
The script /vendor/bin/init.asus.zram.sh uses the property
vendor.zram.enable
to determine if a swap device should be created and the property
vendor.zram.disksize
for the (new) size for the swap device.
If the property vendor.zram.enable is set to 1 but the property vendor.zram.disksize is not set the script uses a default value for the size of the swap device depending on the amount of installed memory.
To create a swap device via a Magisk Script (or change the config of the swap device created by default) it's sufficient to just set the two properties to the approbiate values and execute the init script , e.g.
Note:
This must be done as user root.
Code:
cat >/data/adb/service.d/0010create_swap_device.sh <<EOT
#!/system/bin/sh
# there is a missing leading slash (/) in one of the commands in the file /vendor/bin/init.asus.zram.sh
# therefor the working directory when executing the script must be /
#
cd /
#
# enable creating the swap device
#
setprop vendor.zram.enable 1
#
# use a 512 MB swap device
# The default unit for vendor.zram.disksize is bytes; use the prefix M for megabytes or G for gigabytes
#
#
# Do not set this property to use the default value for the swap device (which is depending on the installed memory)
#
setprop vendor.zram.disksize 512M
#
# now (re)create the swap device
#
/vendor/bin/init.asus.zram.sh
EOT
chmod 755 /data/adb/service.d/0010create_swap_device.sh
To disable the swap device at all use this Magisk script:
Code:
cat >/data/adb/service.d/0010disable_swap_device.sh <<EOT
#!/system/bin/sh
# there is a missing leading slash (/) in one of the commands in the file /vendor/bin/init.asus.zram.sh
# therefor the working directory when executing the script must be /
#
cd /
#
# enable creating the swap device (-> necessary to delete an existing swap device)
#
setprop vendor.zram.enable 1
# new size for the swap device (0 = do not configure a swap device)
#
setprop vendor.zram.disksize 0
#
# now (re)create the swap device (-> only delete an existing swap device)
#
/vendor/bin/init.asus.zram.sh
EOT
chmod 755 /data/adb/service.d/0010disable_swap_device.sh
Notes:
See https://forum.xda-developers.com/t/...droid-12-from-asus-for-the-zenfone-8.4495085/ for how to reconfigure swap in the Original Android 12 from ASUS for the Zenfone 8
Please note that the device /dev/block/zram0 is created in the RAM but the memory for the device /dev/block/zram0 device is only allocated on demand - e.g.:
Code:
#
# free memory with a free swap device on zram0 with 6 GB is about 2783735808 (about 2 GB)
#
[email protected]_I006D:/ # free
total used free shared buffers
Mem: 7612489728 4828753920 2783735808 13639680 15556608
-/+ buffers/cache: 4813197312 2799292416
Swap: 6442446848 0 6442446848
[email protected]_I006D:/ #
[email protected]_I006D:/ # setprop vendor.zram.disksize 0
[email protected]_I006D:/ # /vendor/bin/init.asus.zram.sh
[email protected]_I006D:/ #
#
# free memory with no swap device on zram0 is about 2802741248 (about 2 GB)
#
[email protected]_I006D:/ # free
total used free shared buffers
Mem: 7612489728 4809748480 2802741248 13750272 15577088
-/+ buffers/cache: 4794171392 2818318336
Swap: 0 0 0
[email protected]_I006D:/ #
[email protected]_I006D:/ # setprop vendor.zram.disksize 4G
[email protected]_I006D:/ #
[email protected]_I006D:/ # /vendor/bin/init.asus.zram.sh
Swapspace size: 4194300k, UUID=4a914375-e28f-4181-850a-87cc792eacbe
[email protected]_I006D:/ #
#
# free memory with a free swap device on zram0 with 4 GB is about 2773835776 (about 2 GB)
#
[email protected]_I006D:/ # free
total used free shared buffers
Mem: 7612489728 4838653952 2773835776 13877248 15581184
-/+ buffers/cache: 4823072768 2789416960
Swap: 4294963200 0 4294963200
[email protected]_I006D:/ #
Update 04.10.2022 /bs
See How to trigger an action when a property is changed for how to implement enabling or disabling the swap device on ZRAM via a property value in the OmniROM or another OS

Magisk Module Keylayout for ps4 controller [HELP]

Hello, I'm new here so please excuse me if I post this in the wrong section.
I have a OnePlus 7t on Android 11 with Magisk installed.
I am trying to swap the R3 with Circle on my controller. In the keylayout file it shows that R3 is in fact Circle but doesn't work in games. ( Reverts to default controller mapping)
I have already edited and successfully changed the keylayout file for my PS4 Controller ( Vendor_054c_Product_09cc.kl ) by creating a magisk module since I'm on a stock Os and cant copy the .kl file over to system/usr/keylayouts . SEE BELOW
Code:
# Copyright (C) 2017 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Sony Playstation(R) DualShock 4 Controller
#
# Mapping according to https://developer.android.com/training/game-controllers/controller-input.html
# Square
key 0x130 BUTTON_X
# Cross
key 0x131 BUTTON_A
# Circle
key 0x132 BUTTON_THUMBR
# Triangle
key 0x133 BUTTON_Y
key 0x134 BUTTON_L1
key 0x135 BUTTON_R1
key 0x136 BUTTON_L2
key 0x137 BUTTON_R2
# L2 axis
axis 0x03 LTRIGGER
# R2 axis
axis 0x04 RTRIGGER
# Left Analog Stick
axis 0x00 X
axis 0x01 Y
# Right Analog Stick
axis 0x02 Z
axis 0x05 RZ
# Left stick click
key 0x13a BUTTON_THUMBL
# Right stick click
key 0x13b BUTTON_B
# Hat
axis 0x10 HAT_X
axis 0x11 HAT_Y
# Mapping according to https://www.kernel.org/doc/Documentation/input/gamepad.txt
# Share
key 0x138 BUTTON_SELECT
# Options
key 0x139 BUTTON_START
# PS key
key 0x13c BUTTON_MODE
# Touchpad press
# The touchpad for this joystick will become a separate input device in future releases
# and this button will be equivalent to left mouse button
# Therefore, map it to KEYCODE_BUTTON_1 here to allow apps to still handle this on earlier versions
key 0x13d BUTTON_1
I've made sure the permissions are set correctly as well as seen in the install.sh
Code:
##########################################################################################
#
# Magisk Module Installer Script
#
##########################################################################################
##########################################################################################
#
# Instructions:
#
# 1. Place your files into system folder (delete the placeholder file)
# 2. Fill in your module's info into module.prop
# 3. Configure and implement callbacks in this file
# 4. If you need boot scripts, add them into common/post-fs-data.sh or common/service.sh
# 5. Add your additional or modified system properties into common/system.prop
#
##########################################################################################
##########################################################################################
# Config Flags
##########################################################################################
# Set to true if you do *NOT* want Magisk to mount
# any files for you. Most modules would NOT want
# to set this flag to true
SKIPMOUNT=false
# Set to true if you need to load system.prop
PROPFILE=false
# Set to true if you need post-fs-data script
POSTFSDATA=false
# Set to true if you need late_start service script
LATESTARTSERVICE=false
##########################################################################################
# Replace list
##########################################################################################
# List all directories you want to directly replace in the system
# Check the documentations for more info why you would need this
# Construct your list in the following format
# This is an example
REPLACE_EXAMPLE="
/system/app/Youtube
/system/priv-app/SystemUI
/system/priv-app/Settings
/system/framework
"
# Construct your own list here
REPLACE="/system/usr/keylayout/Vendor_054c_Product_09cc.kl"
##########################################################################################
#
# Function Callbacks
#
# The following functions will be called by the installation framework.
# You do not have the ability to modify update-binary, the only way you can customize
# installation is through implementing these functions.
#
# When running your callbacks, the installation framework will make sure the Magisk
# internal busybox path is *PREPENDED* to PATH, so all common commands shall exist.
# Also, it will make sure /data, /system, and /vendor is properly mounted.
#
##########################################################################################
##########################################################################################
#
# The installation framework will export some variables and functions.
# You should use these variables and functions for installation.
#
# ! DO NOT use any Magisk internal paths as those are NOT public API.
# ! DO NOT use other functions in util_functions.sh as they are NOT public API.
# ! Non public APIs are not guranteed to maintain compatibility between releases.
#
# Available variables:
#
# MAGISK_VER (string): the version string of current installed Magisk
# MAGISK_VER_CODE (int): the version code of current installed Magisk
# BOOTMODE (bool): true if the module is currently installing in Magisk Manager
# MODPATH (path): the path where your module files should be installed
# TMPDIR (path): a place where you can temporarily store files
# ZIPFILE (path): your module's installation zip
# ARCH (string): the architecture of the device. Value is either arm, arm64, x86, or x64
# IS64BIT (bool): true if $ARCH is either arm64 or x64
# API (int): the API level (Android version) of the device
#
# Availible functions:
#
# ui_print <msg>
# print <msg> to console
# Avoid using 'echo' as it will not display in custom recovery's console
#
# abort <msg>
# print error message <msg> to console and terminate installation
# Avoid using 'exit' as it will skip the termination cleanup steps
#
# set_perm <target> <owner> <group> <permission> [context]
# if [context] is empty, it will default to "u:object_r:system_file:s0"
# this function is a shorthand for the following commands
# chown owner.group target
# chmod permission target
# chcon context target
#
# set_perm_recursive <directory> <owner> <group> <dirpermission> <filepermission> [context]
# if [context] is empty, it will default to "u:object_r:system_file:s0"
# for all files in <directory>, it will call:
# set_perm file owner group filepermission context
# for all directories in <directory> (including itself), it will call:
# set_perm dir owner group dirpermission context
#
##########################################################################################
##########################################################################################
# If you need boot scripts, DO NOT use general boot scripts (post-fs-data.d/service.d)
# ONLY use module scripts as it respects the module status (remove/disable) and is
# guaranteed to maintain the same behavior in future Magisk releases.
# Enable boot scripts by setting the flags in the config section above.
##########################################################################################
# Set what you want to display when installing your module
print_modname() {
ui_print "*******************************"
ui_print " Ps4 Controller Crouch Fix "
ui_print "*******************************"
}
# Copy/extract your module files into $MODPATH in on_install.
on_install() {
# The following is the default implementation: extract $ZIPFILE/system to $MODPATH
# Extend/change the logic to whatever you want
ui_print "- Extracting module files"
unzip -o "$ZIPFILE" 'system/*' -d $MODPATH >&2
ui_print "- deleting package cache"
rm -rf /data/system/package_cache/*
}
# Only some special files require specific permissions
# This function will be called after on_install is done
# The default permissions should be good enough for most cases
set_permissions() {
# The following is the default rule, DO NOT remove
set_perm_recursive $MODPATH 0 0 0755 0644
set_perm $MODPATH/system/usr/keylayout/Vendor_054c_Product_09cc.kl 0 0 0744
# Here are some examples:
# set_perm_recursive $MODPATH/system/lib 0 0 0755 0644
# set_perm $MODPATH/system/bin/app_process32 0 2000 0755 u:object_r:zygote_exec:s0
# set_perm $MODPATH/system/bin/dex2oat 0 2000 0755 u:object_r:dex2oat_exec:s0
# set_perm $MODPATH/system/lib/libart.so 0 0 0644
}
# You can add more functions to assist your custom script code
So basically everything seems to be correct but yet in games and gamepad tester the control functions as default ( R3 is not circle)
I've attached images showing im rooted and have the module succesfully installed and enabled, also showing the permissions of the .kl file in the keylayout folder.
Please help! and thank you in advance.

How To Guide How to make files in /system writable

How to make files in /system writable
In Android 12 and newer /system is mounted read-only can not be remounted read-write anymore.
Sometimes it's useful that one or more files in /system are writable (for example for develop tasks or for testing)
This can be implemented using Magisk (see How to change files in the directory /system for more details)
Example :
Make the file /system/etc/vimrc writable
Note:
In Android 12 /etc is a symbolic link to /system/etc.
Open a (adb) shell as user root and do
Bash:
# create a dummy Magisk module
#
mkdir -p /data/adb/modules/writable_system/system/etc
# copy the file that should be writable to the Magisk module directory
#
cp /system/etc/vimrc /data/adb/modules/writable_system/system/etc/
# make the file in the Magisk module directory writable
#
chmod +w /data/adb/modules/writable_system/system/etc/vimrc
Now reboot the phone.
After the reboot the file /system/etc/vimrc is writable by the user root, Example:
Code:
ASUS_I006D:/ # id
uid=0(root) gid=0(root) groups=0(root) context=u:r:magisk:s0
ASUS_I006D:/ #
ASUS_I006D:/ # ls -l /system/etc/vimrc
-rw-r--r-- 0 root root 3350 2022-11-04 11:36 /system/etc/vimrc
ASUS_I006D:/ # tail -2 /system/etc/vimrc
\ | wincmd p | diffthis
endif
ASUS_I006D:/ #
ASUS_I006D:/ # echo '" Test Comment' >>/system/etc/vimrc
ASUS_I006D:/ #
ASUS_I006D:/ # tail -2 /system/etc/vimrc
endif
" Test Comment
ASUS_I006D:/ #
Only the user root can access the directory /data/adb. Therefor the files configured using this approach are only writable by the user root.
To make a file in /system writable for non-root users use this method:
Open a (adb) shell and execute as user shell:
Bash:
#
# create a directory that is writable for the user shell
#
mkdir /data/local/tmp/writable_system
mkdir /data/local/tmp/writable_system/etc
#
# copy the file that should be writable to that directory
#
cp /system/etc/vimrc /data/local/tmp/writable_system/etc
The next commands must be executed as user root:
Bash:
# create dummy Magisk module
#
mkdir -p /data/adb/modules/writable_system/system/etc
#
# create a symbolic link to the file in the writable directory in the directory with the dummy Magisk module
#
ln -s /data/local/tmp/writable_system/etc/vimrc /data/adb/modules/writable_system/system/etc
Now reboot the phone.
After the reboot the file /system/etc/vimrc is writable by the user shell, Example:
Code:
ASUS_I006D:/ $ id
uid=2000(shell) gid=2000(shell) groups=2000(shell),1004(input),1007(log),1011(adb),1015(sdcard_rw),1028(sdcard_r),1078(ext_data_rw),1079(ext_obb_rw),3001(net_bt_admin),3002(net_bt),3003(inet),3006(net_bw_stats),3009(readproc),3011(uhid),3012(readtracefs) context=u:r:shell:s0
ASUS_I006D:/ $
ASUS_I006D:/ $ tail -2 /system/etc/vimrc
\ | wincmd p | diffthis
endif
ASUS_I006D:/ $
ASUS_I006D:/ $ echo '" Test Comment' >>/system/etc/vimrc
ASUS_I006D:/ $
ASUS_I006D:/ $ tail -2 /system/etc/vimrc
endif
" Test Comment
ASUS_I006D:/ $
Important:
The writable directory can also be in a sub directory in /sdcard. But be aware that /sdcard is mounted late in the boot process so it might be that the overwritten file in /system will be used by the OS when the bind mount points to a non-existent file if using a sub directory in /sdcard.
The changes to the file done using these methods are "persistent" as long as Magisk is installed in the boot partition.
To restore the file with the original contents after each new reboot of the phone without removing the writable config open a (adb) shell as user root and execute:
Bash:
#
# restore the file /data/adb/modules/writable_system/system/etc/vimrc from the original file /system/etc/vimrc
#
# this must be done before Magisk creates the bind mounts
#
echo "cp /system/etc/vimrc /data/adb/modules/writable_system/system/etc/vimrc">/data/adb/post-fs-data.d/restore_vimrc.sh
chmod 755 /data/adb/post-fs-data.d/restore_vimrc.sh
Now the file in the dummy Magisk module will be restored with the contents of the original file from /system after each reboot
To temporary access the original file from /system just stop the Magisk daemon, Example:
Code:
ASUS_I006D:/ # echo '"Test Test' >>/etc/vimrc
ASUS_I006D:/ #
ASUS_I006D:/ # tail -1 /etc/vimrc
"Test Test
ASUS_I006D:/ #
ASUS_I006D:/ # id
uid=0(root) gid=0(root) groups=0(root) context=u:r:magisk:s0
ASUS_I006D:/ #
ASUS_I006D:/ # magisk --stop
ASUS_I006D:/ #
ASUS_I006D:/ # id
uid=0(root) gid=0(root) groups=0(root) context=u:r:magisk:s0
ASUS_I006D:/ #
ASUS_I006D:/ # tail -1 /etc/vimrc
endif
ASUS_I006D:/ #
Note
Stopping the Magisk daemon will disable all bind mounts done by Magisk.
Restarting the Magisk daemon will not re-create the bind mount - to re-activate the bind mount for the writable file after stopping the Magisk daemon the phone must be rebooted.
To make more then one file writable in a sub directory in /system you can also replace the complete folder using these commands as user root:
Bash:
#
# make all files in /system/etc writable by the user root
#
mkdir -p /data/adb/modules/writable_system/system/etc/
cd /system/etc
find . | cpio -pdum /data/adb/modules/writable_system/system/etc/
touch /data/adb/modules/writable_system/system/etc/.replace
Now Magisk will replace the directory /system/etc with the directory /data/adb/modules/writable_system/system/etc after the next reboot
Notes
You should test these commands with a not important file like /system/etc/vimrc before changing important files.
It is NOT recommended to use this approach on productive phones.
See How to change any file or directory using Magisk for another approach to change files on read-only mounted filesystems.
Trouble Shooting
As always: If something does not work like expected check the Magisk log file /cache/magisk.log and also check the infos in this post.

Does this method require root on device?

FormulaSea said:
Does this method require root on device?
Click to expand...
Click to collapse
yes

Is there any method don't require root?

This looks interesting. Are you using OverlayFS for this? Looks like you did quite the research on this
Read-only is boring even as root. It's time for some RW baby

FormulaSea said:
Does this method require root on device?
Click to expand...
Click to collapse
I don't know a method to do this without root access.
But you can disable the root access in Magisk after implementing the changes . You could even uninstall tne Magisk app afterwards (but not the Magisk part from the boot partition)
regards
Bernd

lebigmac said:
This looks interesting. Are you using OverlayFS for this? Looks like you did quite the research on this
Read-only is boring even as root. It's time for some RW baby
Click to expand...
Click to collapse
I don't know what exactly you mean by "OverlayFS" - I use MagiskModules to modify files in /system and as far as I know Magisk used bind mounts to implement it.
>>Read-only is boring even as root.
Correct, but if you made the changes directly in /system, they would not survive the next OS upgrade.
One of the great advantages of this feature of Magisk is that it survives an OS upgrade - so as long as the change is compatible with the installed OS version, it only needs to be done once.
regards
Bernd

Thanks it worked on the audio folders on my 7t pro but didn't work on the boot animation folder. Both folders appear in the adb though with there files. Let me know op if you figure out how to do the boot animation folder it's moved to /my_product/ instead of /system/ I see that the my product folder and boot animation appear in the adb modules like the audio folder does and I swapped files the same way as with my audio modding but the changes for boot didn't take effect.

cbomb1337 said:
Thanks it worked on the audio folders on my 7t pro but didn't work on the boot animation folder. Both folders appear in the adb though with there files. Let me know op if you figure out how to do the boot animation folder it's moved to /my_product/ instead of /system/ I see that the my product folder and boot animation appear in the adb modules like the audio folder does and I swapped files the same way as with my audio modding but the changes for boot didn't take effect.
Click to expand...
Click to collapse
/my_product is not in the list of folders supported by Magisk so that may not work
Please post the output of these commands (executed as root user):
df -h
mount
ls -ald /*
ls -lZd /my_product
and a
ls -ldZ $( find /data/adb/modules/ )
and
cat /cache/magisk.log
(or attach the log file to the post if too big)
regards
Bernd

Here is this the correct log file. Thank you for responding to me.

cbomb1337 said:
Here is this the correct log file. Thank you for responding to me.
Click to expand...
Click to collapse
can you also post the output of the OS commands listed?

I Don't know how.

It didn't let me add the log here. Sorry that's it's cut and paste I tried a few termux commands to save a log but the were blank. I don't understand how to do it right.
Edit here I managed to upload the log to drive
https://drive.google.com/uc?id=1uWurf_462b5uLC_D21SFcgLcBWiXQZOn&export=download

bnsmb said:
can you also post the output of the OS commands listed?
Click to expand...
Click to collapse
Linefeeds are missing in that file so it's very hard to interpret the file contents correct
Can you do in a adb shell on the phone:
Bash:
(
set -x
set -v
su -
echo
df -h
echo
mount
echo
ls -ald /*
echo
ls -lZd /my_product
echo
ls -ldZ $( find /data/adb/modules/ )
echo
) > /sdcard/Download/oscmds.log 2>&1
then
Bash:
gzip /sdcard/Download/oscmds.log
and post / upload the file
/sdcard/Download/oscmds.log.gz
regards
Bernd
and

Here is the gzip I wasn't sure what was going on after entering that first command the termux was frozen for a few minutes. Also With the folders in the module folder and them being a copy of the original folder is it ok to delete them as a whole folder to remove the rw and revert it of needed. I tried it and didn't see any issues doing it but wanted to know if it reverted it properly and does deleting the module folders make me lose anything original that was in it or is my stock stuff safe because it's through magisk.

cbomb1337 said:
Here is the gzip I wasn't sure what was going on after entering that first command the termux was frozen for a few minutes. Also With the folders in the module folder and them being a copy of the original folder is it ok to delete them as a whole folder to remove the rw and revert it of needed. I tried it and didn't see any issues doing it but wanted to know if it reverted it properly and does deleting the module folders make me lose anything original that was in it or is my stock stuff safe because it's through magisk.
Click to expand...
Click to collapse
Looks like /my_product is a directory in the root filesystem but on the other hand there is a mount point called /mnt/vendor/my_product so I'm not sure about that.
If /my_product is really only a separate directory in the root filesystem the only method to change it is to manipulate the ramdisk used for booting the phone (only if the phone is using a ramdisk, of course).
Can you check if there are other directories called my_product:
find / -type d -name my_product 2>/dev/null
And, if there are any, compare the files in that directory with the files in the directory /my_product?
regards
Bernd

The only folder that has the same boot animation files is the /dev/ ones and the mnt one like you said.
It's all good if it can't be done i just found a magisk module before which works for flashing my boot animation

cbomb1337 said:
The only folder that has the same boot animation files is the /dev/ ones and the mnt one like you said.
Click to expand...
Click to collapse
Then it can't be done using the standard Magisk feature for making r/o mounted filesystems read-write.
cbomb1337 said:
It's all good if it can't be done i just found a magisk module before which works for flashing my boot animation
Click to expand...
Click to collapse
OK, do you have the URL?
And you could just check the contents of the zip file with the Magisk Module on how it's implemented
regards
Bernd

bnsmb said:
Then it can't be done using the standard Magisk feature for making r/o mounted filesystems read-write.
OK, do you have the URL?
And you could just check the contents of the zip file with the Magisk Module on how it's implemented
regards
Bernd
Click to expand...
Click to collapse
I read the module it mentions binding. I don't understand none of it :/ I upload the module here and removed the boot animation to make it small.

cbomb1337 said:
I read the module it mentions binding. I don't understand none of it :/ I upload the module here and removed the boot animation to make it small.
Click to expand...
Click to collapse
Cool -- that's the solution I also found in the meantime (and successfully tested it on my Zenfone 8)
In principle the module does for the bootanimation file what Magisk does if you replace some directories or files in /system
I will write a general HowTo how that works today or in the next days
regards
Bernd