Can't write to /sys/class ?? - Android Q&A, Help & Troubleshooting

Galaxy S3 rooted + unlocked
Can someone tell me how to write to "/sys/class" files? I have checked to make sure that the files I want to modify have permissions to 0777.
From terminal I enter..
"echo 1 >/sys/class/lcd/panel/gamma_mode"
I am still unable to change the setting. What gives?? What am I doing wrong?
There must be a way right??
Any help is appreciated!!!!!

You have a quoting problem there try it like this.
su
echo "1" >/sys/class/lcd/panel/gamma_mode

Unfortunately it still doesn't change the setting. If I go straight to the gamma_mode file and change it with root explorer, save and exit it will go right back to it's default setting. It will not hold the new value. It's value is currently 2. I can't change it to anything else. Same thing with any of the files located there such as contrast and brightness. Permissions are set to write but they immediately go back to there default settings if you try to change them.
I seem to have this issue with all files in /sys/class.

razz1 said:
Unfortunately it still doesn't change the setting. If I go straight to the gamma_mode file and change it with root explorer, save and exit it will go right back to it's default setting. It will not hold the new value. It's value is currently 2. I can't change it to anything else. Same thing with any of the files located there such as contrast and brightness. Permissions are set to write but they immediately go back to there default settings if you try to change them.
I seem to have this issue with all files in /sys/class.
Click to expand...
Click to collapse
Hi, I am knowing this thread is very old, but did you find a solution? I am having the same issue on my galaxy s7 rooted (4 years later )

Related

LCD Density Changer problems

i am on rooted stock ATT 2.2 firmware. I have busybox installed. Tried LCD density changer app from market but everytime i try to adjust the setting, the phone freezes and the only way to start back is by removing the battery. phone starts back up fine at 160 dpi again.
i have tried 180, 200, and 220 all with same results. any ideas what the problem is?
If you are using a rooted phone browser to build.prop, mount it R/W (root explorer e.g), and edit it.
You should be able to change it there manually.
In the /system/build.prop file, add this:
ro.sf.lcd_density=XXX (where XXX is the density number you want 160/240/etc)
Save, restart your phone and there you go.
MySeLfPT said:
If you are using a rooted phone browser to build.prop, mount it R/W (root explorer e.g), and edit it.
You should be able to change it there manually.
In the /system/build.prop file, add this:
ro.sf.lcd_density=XXX (where XXX is the density number you want 160/240/etc)
Save, restart your phone and there you go.
Click to expand...
Click to collapse
yeh, i saw that manual method but was afraid to try because i wasn't sure i'd be able to easily recover if there was a problem.
fortunately, i found a different app on the market "LCDDensity!" that works just fine. There is no preview and you have to reboot to make the change, but it does a fast reboot and it works flawlessly.
Thanks for the Help!
mongofrye said:
yeh, i saw that manual method but was afraid to try because i wasn't sure i'd be able to easily recover if there was a problem.
fortunately, i found a different app on the market "LCDDensity!" that works just fine. There is no preview and you have to reboot to make the change, but it does a fast reboot and it works flawlessly.
Thanks for the Help!
Click to expand...
Click to collapse
Tried it n it worked but after a full reboot, it reverts back to normal 160 density
MySeLfPT said:
If you are using a rooted phone browser to build.prop, mount it R/W (root explorer e.g), and edit it.
You should be able to change it there manually.
In the /system/build.prop file, add this:
ro.sf.lcd_density=XXX (where XXX is the density number you want 160/240/etc)
Save, restart your phone and there you go.
Click to expand...
Click to collapse
I cant seem to find this line in my build.prop
im using AWS 345 build rooted and Ive done this before with previous phone so im familiar with it but ive looked at least 5 times for that line but its nowhere to be found..
is there any other way???
ducehlmg said:
Tried it n it worked but after a full reboot, it reverts back to normal 160 density
I cant seem to find this line in my build.prop
im using AWS 345 build rooted and Ive done this before with previous phone so im familiar with it but ive looked at least 5 times for that line but its nowhere to be found..
is there any other way???
Click to expand...
Click to collapse
If the line doesn't exist, just add it. For some reason many of the stock Streak build.prop's don't have it in there. But, just add it and then you can tweak to your heart's content. That's what I did, and I'm on LCD=200 now.
mellojoe said:
If the line doesn't exist, just add it. For some reason many of the stock Streak build.prop's don't have it in there. But, just add it and then you can tweak to your heart's content. That's what I did, and I'm on LCD=200 now.
Click to expand...
Click to collapse
yea i figured that out but thanks for the tip... i set mine to 190 & i also grabbed ur wallpaper from the Screenshot thread.. so thanks for that too
MySeLfPT said:
If you are using a rooted phone browser to build.prop, mount it R/W (root explorer e.g), and edit it.
You should be able to change it there manually.
In the /system/build.prop file, add this:
ro.sf.lcd_density=XXX (where XXX is the density number you want 160/240/etc)
Save, restart your phone and there you go.
Click to expand...
Click to collapse
What did you use to edit the file?
mid_life_crisis said:
What did you use to edit the file?
Click to expand...
Click to collapse
Root Explorer. That's what I use. It is a paid app, but the best file explorer I've found. I'm a big fan.
mellojoe said:
If the line doesn't exist, just add it. For some reason many of the stock Streak build.prop's don't have it in there. But, just add it and then you can tweak to your heart's content. That's what I did, and I'm on LCD=200 now.
Click to expand...
Click to collapse
Worked for me. On 345 with density=180! Thanks mellojoe!
Try font changer if you don't want to meddle with build.prop.

[Q] Change a system setting missing from the UI directly?

I have a Lenovo S939 (Android 4.2.2, rooted) and the setting to change the default notification sound is missing. Is there a good app that can be used to browse all system settings and make changes directly (something like regedit in Windows)? Or can this setting be changed in the file system by editing some preferences file? If so, how can I find it?
James Bond 007 said:
I have a Lenovo S939 (Android 4.2.2, rooted) and the setting to change the default notification sound is missing. Is there a good app that can be used to browse all system settings and make changes directly (something like regedit in Windows)? Or can this setting be changed in the file system by editing some preferences file? If so, how can I find it?
Click to expand...
Click to collapse
No settings to change that? That's crazy...I've worked on 100s of phones and have never seen that... But the build.prop found in /system typically has the "code" that points to which file to use for the default sounds.
Thanks, checked the file and found this line: ro.config.notification_sound=HeavenNearby.ogg
If changed, will this be picked up on reboot?
James Bond 007 said:
Thanks, checked the file and found this line: ro.config.notification_sound=HeavenNearby.ogg
If changed, will this be picked up on reboot?
Click to expand...
Click to collapse
Yes. Make sure to make a backup of your build.prop first and that the permissions are still 0644 before you reboot or you'll have to restore the entire phone.
I have changed it to another sound file in the same directory and rebooted, but the sound stayed the same, unfortunately.
Edit: I have "fixed" it by copying the desired sound file over the default one.

Tethering[mod] "build prop edit"vs985

hello fellow xda junkies!
HERE IS A SIMPLE WAY TO GET DATA TETHERING THROUGH BUILD.PROP EDIT
NOTE:MESSING WITH BUILD.PROP COULD MESS YOUR PHONE UP BE CAREFUL
Step 1.) download a text editor.i suggest 920 text editor.
Step 2.) you will also need an root explorer so download that also.
Step 3).open up your root explorer and navigate to system/build.prop. and copy that file to another directory. i.e example sdcard/download.then rename
original build.prop file to build.prop.bak
Step 4).open up your text editor and navigate to the directory where you copied the build.prop file
Step 5.)look for this line [they are both close to the end of the build.prop file] "net.tethering.nonprovisioning=true" [once you find it change the true
to false] so it reads "net.tethering.nonprovisioning=false" NOTEDO NOT TYPE THE QUOTATION MARKS!!!
Step 6.) " look for line "persist.data.tethering_oc=1" change the variable 1 to 0 so it reads "persist.data.tethering_oc=0
Step 7.) move the build.prop file that you copied and edited from location you placed it in to its rightful spot in system/.change permissions to rw--r--r
reboot phone and your good to go!works on my vs985 LIKE A CHAMP.
deathsquad737 said:
hello fellow xda junkies!
HERE IS A SIMPLE WAY TO GET DATA TETHERING THROUGH BUILD.PROP EDIT
NOTE:MESSING WITH BUILD.PROP COULD MESS YOUR PHONE UP BE CAREFUL
Step 1.) download a text editor.i suggest 920 text editor.
Step 2.) you will also need an root explorer so download that also.
Step 3).open up your root explorer and navigate to system/build.prop. and copy that file to another directory. i.e example sdcard/download.then rename
original build.prop file to build.prop.bak
Step 4).open up your text editor and navigate to the directory where you copied the build.prop file
Step 5.)look for this line [they are both close to the end of the build.prop file] "net.tethering.nonprovisioning=true" [once you find it change the true
to false] so it reads "net.tethering.nonprovisioning=false" NOTEDO NOT TYPE THE QUOTATION MARKS!!!
Step 6.) " look for line "persist.data.tethering_oc=1" change the variable 1 to 0 so it reads "persist.data.tethering_oc=0
Step 7.) move the build.prop file that you copied and edited from location you placed it in to its rightful spot in system/.change permissions to rw--r--r
reboot phone and your good to go!works on my vs985 LIKE A CHAMP.
Click to expand...
Click to collapse
You know there is already a flash for this and an apk.
Yes i do know this but some like to do it on there own.but hey nice to meet ya!
deathsquad737 said:
Yes i do know this but some like to do it on there own.but hey nice to meet ya!
Click to expand...
Click to collapse
Just checking.
I'm a tinkerer also which is how I figured out the thermal throttling.
Nice to met you.
tech_head said:
Just checking.
I'm a tinkerer also which is how I figured out the thermal throttling.
Nice to met you.
Click to expand...
Click to collapse
Thermal daemon mitigation?is that what you are referring too?
A.L.B/E.B.B
deathsquad737 said:
Thermal daemon mitigation?is that what you are referring too?
A.L.B/E.B.B
Click to expand...
Click to collapse
Actually not.
Instead of trying to stop the thermal mitigation from working I did just the opposite, I changed the parameters on how it operates.
The file /system/etc/thermal-engine-8974.conf.
This file controls what happens to cpu speed at various temperatures.
That is what you tweak and it just works.
I also used ROM Toolbox to change the governor.
tech_head said:
Actually not.
Instead of trying to stop the thermal mitigation from working I did just the opposite, I changed the parameters on how it operates.
The file /system/etc/thermal-engine-8974.conf.
This file controls what happens to cpu speed at various temperatures.
That is what you tweak and it just works.
I also used ROM Toolbox to change the governor.
Click to expand...
Click to collapse
Wow that's heavy I don't know if I have a high enough pay grade to do that lol
A.L.B/E.B.B
deathsquad737 said:
Wow that's heavy I don't know if I have a high enough pay grade to do that lol
A.L.B/E.B.B
Click to expand...
Click to collapse
I can always get you a copy of the file.
tech_head said:
I can always get you a copy of the file.
Click to expand...
Click to collapse
Yes please I pm you
A.L.B/E.B.B
Thank you but...
First of all, thanks for the post. Although I appreciate the helpful post, my phone is now stuck in boot loop . I hate to be the one to open up an old thread but I'm freaking out at the moment due to brick fever :crying: My current setup was a rooted LG G3 VS98512b. My goal was simple, I didn't want to do anything crazy, I just wanted to enable wifi tether now I'm afraid I've lost everything... Is there a way I can get back into the storage of my phone and delete the modified build.prop, remove the ".bak" from the original and be back to the good life? Any assistance is greatly appreciated, this seemed like such a simple modification that led to such a big headache.
It sounds like you might have used an editor on your build.prop that could not handle the file size, resulting in your editted build.prop being truncated. Otherwise, maybe your permissions were left wrong. Either of these will cause your phone to bootloop.
Sent from my VS985 4G using Tapatalk
trent999 said:
It sounds like you might have used an editor on your build.prop that could not handle the file size, resulting in your editted build.prop being truncated. Otherwise, maybe your permissions were left wrong. Either of these will cause your phone to bootloop.
Sent from my VS985 4G using Tapatalk
Click to expand...
Click to collapse
Thanks for the reply. I used the editor recommended in the tutorial, 920 text editor. I followed the instructions word for word, I don't know what the problem is. Maybe its because I have the newest update and this mod was for 10b???As far as the permissions, the phone asked automatically if I wanted to change the permissions. The original build.prop is still there... is there a way I can delete the modified build.prop and replace it with the original? I really wish I would not have followed this tut, it didn't seem like a popular method. There has to be a way to delete the modified build.prop right?
soundmasterx said:
Thanks for the reply. I used the editor recommended in the tutorial, 920 text editor. I followed the instructions word for word, I don't know what the problem is. Maybe its because I have the newest update and this mod was for 10b???As far as the permissions, the phone asked automatically if I wanted to change the permissions. The original build.prop is still there... is there a way I can delete the modified build.prop and replace it with the original? I really wish I would not have followed this tut, it didn't seem like a popular method. There has to be a way to delete the modified build.prop right?
Click to expand...
Click to collapse
Yes you can reflash the firmware or if you don;t want to restore to stock you can use ADB to fix the files and restore your .bak
Digital_MD said:
Yes you can reflash the firmware or if you don;t want to restore to stock you can use ADB to fix the files and restore your .bak
Click to expand...
Click to collapse
Again, thank you for the response. Do you recommend a specific method or tutorial for trying restore the original build.prop? I did search however, because this scenario is so specific I'm not sure there is an exact solution to my problem.
Again, just in case someone else can chime in, I followed the instructions on the first post of this thread (see first post for detailed info). I copied the original build.prop then changed the name of the original build.prop, edited the copy, moved it to the original directory and restarted the phone. Now my phone doesn't make it to the Verizon screen (I think it is stuck in boot loop), the screen stays black and the small led on the left corner flashes blue and green. If I can just get access to the storage I can replace the modified build.prop with the original that is still in the same directory just renamed. It seems like such an easy task but, I just don't know how to go about it I'm a somewhat of an old school tinker, I'm just now getting back into the swing of Android... Thanks in advance!!
Bump
Bump please
This is crazy... I changed 2 values in build.prop for tethering and my phone wont boot now... I didnt install a ROM, change DPI, or make any major changes WTF???
Do you have a custom recovery (twrp)?
Can you connect to your phone with adb?
If you have twrp, search the board for the startup hardware key sequence to reach twrp, else from adb do a reboot recovery.
In twrp, you can select to mount system, then go to advanced - file manager. You can delete the bad build.prop, rename the good one, then set the permissions on the good one. If your good copy of build.prop is on a PC, put it on a flash drive, and use twrp's file manager to get it into your phone.
If you have a saved copy of build.prop on your PC, you can also use adb's push command. (You may also want to look at the adb shell command. The sequence might be to open a shell, delete the bad build. prop, get the right build.prop into the right directory, then chmod the right build.prop so it has the proper permissions.)

Hi xda . I need urgent help !

i installed build prop editor and i saw the option change pixel density
i changed it to 360 and i rebooted the phone and when it rebooted i get force closes and i cant do anything on my phone now...
Any help???Any fix without loosing my apps? cuz i dont want to loose my apps... i have some important things in there...
@gabiabrudan7: you only may reduce dpi, lower 320! So try to restore the old build.prop: if there's a bak-file, you can rename it in TWRP's file manager - otherwise use ADB (if there's access from PC) to move build.prop to PC, change it with an editor, which stores in UNIX-format and move back.
rp158 said:
@gabiabrudan7: you only may reduce dpi, lower 320! So try to restore the old build.prop: if there's a bak-file, you can rename it in TWRP's file manager - otherwise use ADB (if there's access from PC) to move build.prop to PC, change it with an editor, which stores in UNIX-format and move back.
Click to expand...
Click to collapse
thanks for the reply but i already fixed it ... i flashed lollipop mirror and i have no problem now!
thanks anyway!

How to enable USB debugging via TWRP in MIUI (Poci F1) ?

The title says it all.
Already tried:
I tried to pull build.prop and default.prop from the phone and edit them to enable debugging but that results in a bootloop. Also tried another method which requires to unpack a boot.img and edit files in the ramdisk but the ramdisk folder is empty after unpacking boot.img.
Why ?
Ans. I messed up my resolution and DPI and i think i can reset it via adb shell.
Thread here :
https://forum.xda-developers.com/poco-f1/help/help-messed-screen-resolution-dpi-t3945921
Try this:
Pull the file "settings_global.xml" from "/data/system/users/0/"
Search for attribute "development_settings_enabled" and change the "value" and "defaultValue" to 1.
Search for the attribute "adb_enabled" and change the "value" and "defaultValue" to 1.
It should enable the USB Debugging.
gaurav.5125 said:
Try this:
Pull the file "settings_global.xml" from "/data/system/users/0/"
Search for attribute "development_settings_enabled" and change the "value" and "defaultValue" to 1.
Search for the attribute "adb_enabled" and change the "value" and "defaultValue" to 1.
It should enable the USB Debugging.
Click to expand...
Click to collapse
Edited and Replaced the file as per your suggestions but adb isn't still enabled on boot. Also, when i pulled the file back, only the "development_settings_enabled" attribute had stick to "1" whereas "adb_enabled" was still "0"
Any more suggestions as to how to enable it ?
or do you know where the display size and density settings reside in the form of a file so that i can replace them with the correct one .
Fyi i need to enable adb t reset display size and density .
More info here:
https://forum.xda-developers.com/poco-f1/help/help-messed-screen-resolution-dpi-t3945921
I am in real distress. I don't want to lose my apps and settings :crying::crying:
MasterFURQAN said:
Fyi i need to enable adb t reset display size and density .
Click to expand...
Click to collapse
Try this:
Pull the file "settings_secure.xml" from "/data/system/users/0/" and change the value and default vaule for the attribute "display_density_forced" to 375
gaurav.5125 said:
Try this:
Pull the file "settings_secure.xml" from "/data/system/users/0/" and change the value and default vaule for the attribute "display_density_forced" to 375
Click to expand...
Click to collapse
I don't know what I did but I somehow made it work. I was about to give up when I accidentally restored back the nandroid backup and I thought "I might as well give it a last shot". I did a lot of things including copying some of the props and XML files and many more things and it booted without any problems except that it wasn't accepting my lockscreen password which is quite easy to fix. Thanks to you for bearing this with me.
After all of this, I think it isn't possible to enable USB debugging via recovery (or by editing props) on MIUI or maybe it's because I'm still encrypted.

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