text:
Export telegram and whatsapp contacts to vcf?
I have lost most of my contacts on the phone account, but they still exist in my telegram account. How can i move them to phone or export them?

It's very easy to transfer contacts from telegram account to your android smart phone:
Just install a contact backup software from google store like "+contact backup" and after that make a back up from your contacts; it automatically collect all of your contacts from every account that you have on your phone: telegram,google,phone etc.
after completing your back up you can import the created file to your phone or google account.
it's finished

Can you please suggest any such app, with its link? I don't seem to able to find any such app with the particular functionality of backing up for each Account as you say..

For WhatsApp, here's a trick that might work, but you need to use WhatsApp Web to do that:

Download your WhatsApp Contacts with the help of the bookmarklet here.(The contacts get exported as a CSV list)
Now you can convert the CSV file to .vcf using some tools available..
Here's a tool that you can try: CSV to vCard

Unfortunately, I don't find any such tricks for Telegram.


text:
"Priority only" as default mode - Marshmallow
When I try to change the "Notifications mode" using the volume key, it always defaults to "Alarms only" mode, but I would like this to be set as "Priority only".
I know I can swipe down to access "Do not disturb" and set the "Priority only" mode but I want to do it with volume keys
Is there any way to set "Priority only" as default mode when using Volume keys

I wish I could help you. 5.0 and above have terrible volume settings.

@beeshyams I wasn't able to set the priority mode as default mode yet. Can you please share step by step. I am using Nexus 5. Here is another question on this topic http://android.stackexchange.com/questions/150748/how-to-change-default-do-not-disturb-to-priority-only

@beeshyams  Sorry but every time I press my volume button down, I don't see any way to reach the priority mode. Can you please give me the direction to do this?

Also, as you told "silencing the volume + being on Vibrate + further decreasing volume = priority mode" is what I am looking for...

@beeshyams sorry for the delay... I will try this by the weekend and let you know. Thanks and appreciate your effort and help

Alarm mode  is activated when Vol is decreased progressively reaching silence first, next vibrate and on further decreasing the volume (watch closely and you would notice these steps). OP has clarified that this the behavior expected except that desired end mode should be Priority mode instead of Alarm mode
Since we are talking of changing the default behavior of OS, one way could be to root the device and tweak or use an app. automation may be preferred option, since it doesn't involve rooting & modding. Many apps are available. I prefer using MacroDroid , since it is free (upto 5 macros) and easy to learn. To understand how MacroDroid works and required settings (app guides you through the settings - make sure from the app settings you activate ignore battery optimisations, my answer here. The drawback of automation approach is that it won't perfectly replicate the expected behavior and has snags, which are mentioned at  end
You would need two macros for this
First macro would look like this (Triggers / Actions / Constraints are added by +)
Macro : Vol Silent / Vibrate (name of macro )
Trigger : Volume Button Pressed → Volume Down → Update Volume
Actions:

Set MacroDroid Variable → New Variable →Create New Variable→ Give it any name (here ring) and set type to Integer → Set (variable name) → Value = 0

If Clause → Conditions + → Ringer Volume → Vibrate or Silent . Press this If clause and choose Add Child Action. Next,  Set Macrodroid Variable,  choose the variable name (step 1) and set it to 1

Constraints:  No Constraints
Logic: We need to identify when silence or vibrate is reached by Vol Dn  . In the first action we named a variable and set it to 0 and in the second action, we set a flag (MacroDroid variable =1 ) to indicate that silence or vibrate is reached. Not specifying any Constraints means we want the macro to always run
In the next macro, we make sure that if the Volume is further decreased from silence or vibrate state, we set it to Priority Mode. To ensure that it happens only when this state is reached, we use the flag as constraint and re-initialize the variable to 0
Macro : Set Priority Mode (name of macro )
Trigger : Volume Button Pressed → Volume Down → Update Volume
Actions:

Set Priority Mode → Priority

Set MacroDroid Variable (name you chose, here it is ring) → Value = 0

Constraints:  MacroDroid Variable (ring) → Value = 1

OK , I had mentioned that it isn't perfect, mainly because you are trying to override default OS behavior without rooting and modding. So, here are the glitches :

If you pause decreasing volume on reaching Silence / Vibrate, or if you are on vibrate and decrease volume further - it won't work

Sometimes , even if you decrease volume smoothly without pausing, you would still see Alarm mode instead of Priority mode. Reading the app logs indicates that this is because both the micros require a few milliseconds to kick in and by then OS has done it's job !  Workaround is to increase the volume a bit and then decrease it, maybe a couple of times allowing the app to do it's job

From Priority Mode, when you increase the volume, it still displays the same status (unlike in alarm mode) , so you need to manually click End Now

+1 for amazing effort, totally looks like it works (haven't tried though)

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

sort: votes


text:
Help! 25 unkown apps messing with my phone
These apps keep showing up in my data usage screen. I have no idea what they are or where they came from. There are 25 of them by the way. All they seem to do is use up data and interfere with my phones operation. I.E. slowing it down, closing other programs, opening Google play asking me to download one thing or another, pretty sure they've ended a couple of my calls. Though I can't prove it. NO anti-malware picks them up.
If it is an app I've installed causing the problem how do I figure out which one (short of installing them one at a time)? Is there anyway to get rid of them (short of formatting phone again or performing a factory reset)?
I'm not a pro so I need it simply explained. Not dumb either. My phone is not rooted and I'd rather not if I don't have to. It looks like a pain and I'm not great with Linux systems. My phone it a ZTE Rapido LTE model Z932L, Android version 4.1.2. Any help would be great.
Edit: I don't think the question that is similar to mine answers my question. Tho the are very similar. I did not have my phone updated or messed with by the company I bought it from. Its a straight talk phone. To my knowledge there isn't anywhere I could take it. I have factory reset my phone twice and the problem continues. It could very well be something I did (infact that's the most likely conclusion). If it is I need to know what so I don't do it again lol. Also added screen shot of "removed apps," and two more have popped up since I posted this question. I have not uninstalled anything.

Screenshots (click images for larger variants)

Another similar question: An unknown app called 10102 shows up in Data Usage graph

I think these are just the uninstalled apps that have used data.

@GokulNC though that wouldn't explain the slowing-down and closing of other apps. Still, that might be a different unrelated thing; uninstalled apps make sense with those screenshots. // Anthony: Did you uninstall a bunch of apps lately? Have you tried restarting your device and see if those "number candidates" still turn up?

First off let me say thank you for the help. I really appreciate it. @Izzy When I first noticed them ( the numbers) I had not uninstalled anything. Since then I have uninstalled 4 or 5 apps such as 360 secerety and battery doctor. Yes I have restarted my phone and they remain. Wish it that.

@GokuINC I have my doubts as to them being uninstalled apps for two reason one being the number of them and two the is a section called removed app that shows the data they used before being uninstalled. I will replace one of the screen shots to show it. Could they still be apart of an app I uninstalled?

@Anthony the "number" would be the "UID" of the app, which no longer can be resolved to an app name with the app removed (so this makes sense). It also could be a native system process (not being an app), though that might rather be bundled into "Android OS". Also note the icon being the same as for these two, which again indicates it might be one of these two. What irritates me is they don't have an amount of data associated, but are marked "restricted" instead. Why show something in data usage that used no data?

@Izzy That's because I restricted them. Because like most people I've limited data. They range, currently, anything from a few KB to MB. After just a day or so of the showing up. Restricting them causes less issues with my phone. I've tryed letting them run on my home network, in hopes that if they they where apart of the OS in some way, maybe an update or some other system process, but my phone becomes almost useless. If it would help I can undo a few and show what data they have used.

Have you checked with How to know app name by UID already? Maybe that gives a clue.

@Izzy I'm trying to use the emulator. However I don't know which command proment to use. And the ones in the article I've tried so far either they don't do anything, cannot be found, or I don't understand what it means

@Izzy this is the only thing that shows up after using ps l grep command line.                 u0_a100@android:/ $ ps l grep 10402
USER     PID   PPID  VSIZE  RSS     WCHAN    PC         NAMEu0_a100@android:/ $

You've picked the wrong answer (see its 2nd comment). Check the answers from Firelord and Lie Ryan.

@Izzy I don't understand what there talking about.

Firelord's answer will be the easiest approach then. See our adb tag-wiki to get started with ADB, then follow the steps pointed out in the answer.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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“Message Not Sent” notifications for days
I replied to an SMS but my message couldn't be delivered. I presume because the originating number wasn't a mobile number but the fixed line on the sender.
Now I'm getting that notification in the notification bar every 10 minutes or so. How can I get rid of it ?

"Message not sent - Touch to review the message and try again".

When I touch the notification, it opens the SMS app, with the threads list.
I deleted the message thread, tried to clear the cache, restarted the phone...
This was more than one week ago. I waited for the SMSC to give up trying to resend the message (after 3 days I believe). This is not a setting a network issue since I'm able to exchange SMS with other parties without problem.
It's the Android Messaging application version 4.4.4-37.

I installed another SMS application (Handcent next SMS not to name it) and could access and delete the pending message (in Delivery Report / Undelivered).


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Can I export certificates from Credentials Storage
I have several certificates in the Credentials store that I would like to backup. Can they be extracted?
OnePlus 2 running OxygenOS 2.2.0 Android 5.1.1
Not Rooted.

Is your device rooted?

This device is not rooted.

Well, unless you want to modify them it should do without. Certs are stored in a specific directory (/system/etc/security for system certs, /data/misc/keychain/certs-added for user certs) one per file, so you could just copy them to your PC if you like. See this SO answer for details.

/data does not appear to be accessible. Access denied using FX explorer. perhaps I will root the device and have another go.


text:
Charge and USB keyboard through 1 USB port
I have a Samsung Tab E that only has one USB port.
Can I charge the tablet and have a USB keyboard attached at the same time?
I've tried a 3-way cable ( link to Amazon ) but it supplies power to the keyboard, not the tablet.
I've also tried using a USB hub I had lying around, but I couldn't get that to work either.

I contacted Samsung support and their answer was that the single USB port cannot be used for charging the tablet at the same time as providing a data connection.

That was what I pointed out in my answer too !

The most likely way to use a keyboard while charging on a single port device is to use a Bluetooth keyboard.
Failing that, you may need a different 3-way cable.  The keyboard certainly needs power to operate (unless it has internal battery power), but a correctly wired 3-way cable should be able to both power the keyboard and charge the device.  You can verify that there's voltage on the charge pins of the two USB connectors on the 3-way cable, with a meter and suitable fine probes -- though it's very possible that the device will refuse to accept charge if there's a data attachment on the USB port.  You'd have to contact Samsung to verify that.

There are three kinds of USB ports in use (before USB Type C)- data only, charge only and both data and charge
Quoting from How USB charging works

In terms of actual current (milliamps or mA), there are three kinds of USB port dictated by the current specs: a standard downstream port, a charging downstream port, and a dedicated charging port. The first two can be found on your computer (and should be labeled as such), and the third kind applies to “dumb” wall chargers.

Tablets are known to have any of these ports. The port you have for charging is a dedicated charging port (as I suspect ) and will not allow simultaneous data transfer. This is borne out by your observation that the keyboard is getting power when connected with a 3 way cable or even USB hub (more reliable for such requirements)
You can easily verify this by connecting a flash drive through an OTG cable and transfer files. If it doesn't work (as I suspect), you have your confirmed answer
It may turn out to be a futile attempt by introducing additional hardware to meet your goal if the port itself cannot support. You may like to first validate this by seeking a confirmation from OEM, in case my reasoning current appeal to you


text:
Sound from VLC video after locking screen
So I'm watching a video talk in VLC on my Samsung I9305 rooted stock 4.4.4 with Xposed Framework, and I want to lock the screen and put the phone in my pocket, but still continue listening to the audio of the talk. Is it possible to do this with VLC, or do I have to switch to another media player?

Definitely possible but depends upon on what length you would go to keep VLC as the choice of player here. Example, you can put the brightness to 0 and cover the screen with an overlay in blocking mode. Also, disable all the navigational hardware buttons too when VLC is active. It can be done easily but do you want this mess?

@ Firelord It turns out this is actually a native function of VLC for Android! It's very easy, I have answered my own question.

It turns out this is actually a native function of VLC 1.7.4 (and probably previous versions too) for Android.

Click the three horizontal lines in the top left corner (on the file selection screen, not while a video is playing).
Click on "Preferences".
Tick the "Play videos in background" box.
Play a video.
Lock the screen.
Keep listening to the audio from that video!

It seems you can't combine Picture-in-picture (aka Popup player) with the play in background, as for example Yoube Vanced does.
It would be nice to be able to play the video in the popup player + keep the audio playing when locking the screen.

i have Huawei mate 9 and i have found one resolution which is Phone Battery is locking VLC player to run in back ground see attached screenshots which we have to enable.

Those options are specific to Huawei phones, so while they might be helpful to other Huawei customers, they won't help with the Samsung phone the question is about.

@DanHulme Interestingly, shortly before this answer was posted, I switched to a Huawei Mate device. So this answer was almost like an update for my new device. Just funny.

I had the same problem on a Samsung Note 8, even with "Play videos in background" setting turned on. In the latest version of VLC (v3.3.4), the "Play videos in the background" option is a little different, it's actually "Background/PiP mode" with 3 options:

Stop
Play videos in background
Play videos in Piciture-in-picture mode

The issue for me was the power saving setting, similar to THE PATHAN's answer for their Huawei Mate 9.
Here's how to fix it on a Samsung:

Open Settings
Open Apps
Find and open VLC
Click "Battery"
Toggle "Allow background activity" to on

Without this setting, audio playback will be stopped about 30 seconds after locking the phone regardless of the "Background/PiP mode". However, with "Allow background activity" turned on, audio playback will continue even with the "Background/PiP mode" set to "Stop".

Would something like this work for you? YouTube player
That is a YouTube player that plays after the screen is locked.

I already have this function for Youtube. I'm looking for the same function with VLC or another video player.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Droid Explorer app does not show hidden files
Droid Explorer does not show hidden files. Some "root explorer" apps show hidden files, e.g. on /data/data etc., but Droid Explorer does not. Of course, ES File Explorer also does not show these, it shows only files which can be seen by the phone's own file explorer, but some "root explorers" show these.
How I can adjust Droid Explorer to show hidden files?

My original project was this, about 8 hour ago:
https://www.quora.com/I-have-Crypt7-files-of-my-girlfriends-WhatsApp-How-can-I-read-her-messages
I try copy open my whatsapp messages using any this-type way. Problem is, it is not any file explorer on Android which can 1) show and 2) copy any this type "hidden" file. Eg. this ES can show this "data" but is empty- even "show hidden files" is active. After several tests I found one "Root explorer" which can show this data/data/com.whatsapp etc, BUT copying is not possible.
So- how to show Droid Explorer hidden files? Or any better explorer?

Try ES file explorer.

@VivekJi it was already mentioned that ES Explorer was tried, and that it shows "data" as empty. Both in the comment above yours, and in the original question.

Whatsapp messages aren't where you think they are. They are under /sdcard/WhatsApp/Databases/ and are stored as encrypted msgstore.db.crypt8 files. The mentioned folder path is not hidden in any way.

I am the developer of this Droid Explorer which does show hidden files.
If you are talking about this Droid Explorer (by Asif Wani) then I can't help you, as I have nothing to do with that app. I would suggest you contact the developer of that app. His contact info is at the bottom of the link I posted.
I am going to assume you mean the App for Android Devices, not my application that runs on Windows...
In the settings of that application, there is the option:

Now, is your device rooted? Because you will not be able to see files in the /data/apps/ or /data/data/ if you don't have root. Root requires more than just a "root enabled" file explorer. And it will show "empty folders" if you do not have access to view the files. This is the case with all file explorers, including the one that I am the developer for.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
My Music Won't Appear on my OnePlus One
On my OnePlus One, which is currently running Android version 5.1.1 and Cyanogen OS version 12.1, isn't finding music on my device. I got the music onto my phone with my Chromebook, a HP 14, and simply moving the files to my phones "Music" folder. Once disconnected from my laptop, the music won't appear in the "Play Music" app. I know the files are on my phone, since they appear when I look in my file manager.
I've tried hitting the "refresh" button on both the music app and file manager, in addition to clearing the cache on both the applications. I've also rebooted my phone numerous times, and tried using a SD re-scanner with no avail.
This problem has happened on my phone before, and I solved it by clearing all the music data and putting it all back on my device. Still, I would really prefer not to do this, since it is kind of a pain.
Thank you so much!

I thought that Play Music sees the music you've uploaded to Google Play Music (google.com/music), not the music that is locally saved on your device.

@RMarkwald It should see both

@Mark What format is the music in?

Have you tried whether other music apps can see your files? If they don't, it might be worth clearing cache and data of the media library, to force the media scanner to entirely rebuild it. Also watch out for any .nomedia files in the path to those files.

@LJD200 Its MP3.

Go to Settings -> Apps -> All apps - Media Storage and do force stop and clear data. Reboot and tell us the results. Alternatively, if the Android is rooted, clear the contents of the directory /data/data/com.android.providers.media/ and reboot.

Community bump prevention: this question was closed because the question seems to have been abandoned (OP hasn't visited the network for more than 5 years, and no answers have score above 0). If anyone can evaluate the existing answers, feel free to vote accordingly and reopen the question (or mod-flag the question requesting for reopening). For anyone else having the same issue, please post a new question and refer to this question as additional context.

An Android Central thread discusses this issue and has several things to try:

Force stop Google Play Music and clear its data before reopening it. This may lose some data such as playlists but hopefully not the music itself.
Uninstall and reinstall all the updates to Google Play Music.
Ensure that the folder that the music is stored in or any parent folders don't have .nomedia files in them. You may need to enable hidden files in your file manager to see these files.

Unfortunately, some of these solutions seem temporary but it may be worth a try.

I tried all that you suggested. The force stop did nothing, as well as the update suggestion. Clearing the data lost MORE music. Thanks for the suggestions anyway. I think I'm just going to replace all the music, and see if that works.

@Mark Very sorry about not being able to fix the issue and the data loss. This isn't the first time I've heard about this issue on a OnePlus One but that could be coincidence; I don't know whether the issue is related to the device... Hopefully replacing all the music solves the issue permanently. I'm not sure what else to suggest.

From OP's (now deleted) comment,

In the end, I didn't need to replace all my music. I merely connected my phone via USB cord to my laptop and browsed through my music files. I think that it rescanned my files, and the songs reappeared on the device.


text:
Nexus 7 is not booting up after android marshmallow update
I received OTA for my nexus 7 tablet few days back and since then my device is not booting up. Can someone please help how to get it working ?

A few questions about your issue: Did your device stop booting immediately after installing the OTA or several days after?
Also, is your device stuck on the boot animation or do you just get a blank display?
Finally, is your Nexus 7 a 2012 or 2013 model?

@LJD200 it's 2013 device and it stopped after update installation. I forgot to charge after update and once it shut down, it never booted again.

Download the Nexus Root Toolkit from here.  It has options to restore any Nexus device back to its factory settings, including bricked or boot looping devices, under the Flash Stock + Unroot button.  You should select the option Current status of Soft-Bricked / Bootloop.  The toolkit will walk you through, step by step, restoring your Nexus to working condition.
You may lose any data stored on the device.

This should certainly work but solutions such as clearing the cache and/or data partition may be more desirable as first steps since they do not result in data loss...

That's certainly worth a try, but that's harder for a newbie to do, especially if they haven't installed a custom recovery.  Based on what the OP said about the battery dying in the middle of an update, I'm willing to bet that the the system or boot partition was only partially written and is corrupted though.  Bigger guns are needed to fix that.

You can wipe these from the stock recovery. The OP says that the device ran out of battery after the update. I agree that flashing stock will almost certainly fix the update but I think it's worth trying some other things before building up to this if they don't work.

You should add an answer then, I wasn't aware they stock recovery key you do that, others may not either.

Bradley Uffner's answer is very good but try the following first and then follow his advice if these solutions fail.

Boot into stock recovery (guide here) and wipe the cache partition then reboot.
If that fails, boot into recovery in the same way and wipe the data partition.

With power and volume button also my tables is not coming up. It doesn't load recovery screen also.

It's very unlikely that you can't access the bootloader so please try again and report back. When the device is turned off, press the Power and Volume Down Keys together until the Android symbol appears (this should take around 5 seconds to appear but hold for more like 10 if it doesn't appear at first). If this doesn't work then this issue may not be fixable and certainly not easily. It's not really possible that running out of battery while Android is running could cause an issue involving loss of bootloader access. Hope we can sort out this issue!


text:
Go back in Chrome browser
New Android user here with what I considered to be a pretty basic question.
How do I go back in Chrome?
I know the "obvious" answer is to hit the back soft button, but that doesn't actually go back to the last page but rather to the last activity across your entire phone. For example if you're using an application other than chrome, and then switch to Chrome, and hit the back button it will not bring you to the the previous web page but rather to the previous application. At this point I don't know how to access to previous page.

Strange. Back button in my Chrome behaves as it should even Chrome is recently switched to. I'm using v46.0.x though, not the latest.

It appears that the problem is old and hasn't been fixed yet. Chrome 37 back button

As far as I can tell, there isn't any issue filed for it? Perhaps the behavior is by design. It's not entirely clear you'd want the OS back button to go back a page since the usual behavior is to back back to the last interaction, phone wide. If the behavior was changed to always go back to a prior page you'd break the back button for another set of uses.


text:
Modification to WhatsApp apk
So, basically I wanted to modify the looks of my WhatsApp (WhatsApp 2.12.317) application in my Android. This is what I have done:
1.Decompiled the APK using apktool 2.0.2
2.Did the necessary editings.(mostly in strings.xml and colors.xml and a few PNGs)
3.Recompiled the APK
4.Signed it using APK signer
Problem arises when I install and run my modded whatsapp. The SMS verification step fails. When I go for the "Call Me" option it says "Client has been modified ....". So what do I do? Did i go wrong somewhere? Plz help.

This question may possibly be off-topic as Android Enthusiasts does not cover Android development. I suspect that WhatsApp run server-side verification to make sure that people do not run modified clients but I cannot be sure. If this is the case, I do not know whether this can be fixed.

Sounds like it is compiled in a manner where it will not let you modify the original APK file, and will cause errors.

WhatsApp has a history with unofficial clients in the past.  My guess is that the developers built some sort of authenticity check into the application to ensure only unmodified official clients are connecting to their network.  Your modifications  cause this test to fail, and you will not be able to fix this without knowing the authentication logic.

Is it the unofficial signature of mine that causes it??

The resigning signs the apk with a new certificate, but not the original from WhatsApp. If that was possible nobody would create commercial software for Android as it would be too easy to hack.
Google play services have a number of measurements in place to discover modified APKs, and the error you see simply means WhatsApp is using them.

Hm.. I get it. This means I need to find a way to stop the communication between Whatsapp and Google Play services. What if I uninstall Google Play services? Will it work?

Then it will probably fail with a message saying you need Play Services... The whole idea of this protection is to stop people from using a modified APK.  In theory you should be able to modify the compiled code such that it disables the checks, but I think it is a lot of work to find all places where the results are checked.


text:
Using command-line to boot into primary and secondary ROM of MultiROM
I've a OnePlus One with unlocked bootloader, modified TWRP v2.8.6, unofficial MultiROM v32k, MultiROM Manager v1.186, Cyanogen OS 12 as primary and several Android 5.1 secondary ROMs. I don't have any non-Android secondary ROM.
I created a Android backup script in my PC which requires me to boot into a particular ROM of mine for backup to take place. This is not an XY problem and hence I need not to discuss anything about the flexibility of backup. I must boot into a particular secondary ROM (say S1).
At present, I'm using automation, Tasker precisely, which using time trigger launches MultiROM and uses combination of input tap commands to navigate to S1's entry and taps it to boot into it. As you may have guessed, this approach is mundane and is bound to fail should the user deliberately or inadvertently touches any soft/hard button or interacts with UI of the active app during which the series of input commands are in use.
I'm absolutely aware about AutoInput, Xposed Additions Pro apps and screen pinning of an app, where the former two  allows independently disabling soft/hard keys for an active app. AutoInput can even simulate recorded touches. However, none of them can disable input from touchscreen, with touch input being the biggest cause of failure with current solution.
Being unable to find out a way to block touch input on-the-fly, I decided to figure how MultiROM Manager app causes a device to boot into a particular ROM. It was a hopeless journey to begin with, given that the keywords viz. command, multirom, adb, boot, secondary, primary ROM, are found wherever MultiROM is mentioned. Since even advanced web search didn't benefit me, I decided to peek into the output of logcat and see whether it gives me something useful. Once again, nothing of any good use.
I found myself left with the choice to contact Vojtech Bocek (Tassadar, the original developer of MultiROM) for the solution or peek into the source code of the app. Deciding to go with the latter choice, during my exploration I stumbled upon these lines in MultiROM.java

public void bootRom(Rom rom) {
    String name = (rom.type == Rom.ROM_PRIMARY) ? INTERNAL_ROM : rom.name;
    Shell.SU.run("%smultirom --boot-rom='%s'", m_path, name);
}
Being through with libsuperuser already, I took an educated guess that Shell.SU.run("%s/multirom --boot-rom='%s'", m_path, name) most likely corresponds to the command run in a shell with superuser privilege.
And, this is the end of the story since I've checked all the locations under $PATH and none of them contains the binary named multirom.
So, how do I boot into a particular ROM now?

Now that I think about it, I realized that I can use Tasker's scene in overlay blocking mode over the screen except at places where input tap would be performed.

I searched for the string multirom --boot-rom and came across an interesting paste (copy) posted by an untitled guest, with these relevant lines:

<alvinmobile> How do you autoboot other rom in a secondary rom?
<alvinmobile> I mean where do you store the info?
<Tassadar> it runs "multirom --boot-rom=nameoftherom" in su shell, and MultiROM takes care of that - it loads ROM list as usual and either directly kexecs the required kernel or sets force-autoboot into rom X (which saves into multirom.ini) and reboots

I was on the right track as it seems. I suddenly realized that multirom installer zip may be the final piece of the puzzle. And it was, since it contains the multirom binary and uses extract_multirom.sh script to place the binary et al into /data/media/0/multirom (accessible with root access only).
As for finding the name of a ROM, it is what you see in the ROM list in the app or the name of the top-level directories under /data/media/0/multirom/roms.
Boot into the ROM
(Prefix adb shell in commands if you want to use adb to test them.)
The command is very simple:
su -c /data/media/0/multirom/multirom --boot-rom=ROM_NAME

Replace ROM_NAME with the name of the ROM to which you want the device to boot into. It is case-sensitive so Internal works but internal doesn't to boot into primary ROM.
I've not tested passing a ROM's name consisting of special characters but whitespace can be escaped using '' and \. E.g., the name Xenon HD can be passed as 'Xenon\ HD' and  the whole command would be
su -c /data/media/0/multirom/multirom --boot-rom='Xenon\ HD'

You can create a symlink for convenience.
Trial and Error
With a bit of testing, I reached the conclusion that the ROM can be switched by editing the multirom.ini file alone, followed by an ordinary reboot instruction. Among other lines in that file, these are the most useful ones:

current_rom=COS12
auto_boot_seconds=5
auto_boot_rom=Internal
auto_boot_type=0

Here,

current_rom - contains the name of the currently active ROM or the last active ROM if the device powers off without an instruction to be switched into an another ROM
auto_boot_seconds - timeout to boot into default ROM
auto_boot_rom - the ROM that should be booted into after timeout
auto_boot_type - governs whether there should be a direct switch between ROMs or should the UI for ROM selection be shown during boot

(There are no sources to support the claims. I've reached the conclusion based on my experiment only.)
Let's assume that your active ROM is named COS12, internal ROM is named Internal and you want to switch to Xenon HD. Switch it this way:
(Requires Busybox)

su -c cp /data/media/0/multirom/multirom.ini /data/media/0/multirom/multirom.ini.orig       # one time command and optional, but it is safe to make backup always
su -c sed -i 's/current_rom.*/current_rom\=ROM_NAME/g' /data/media/0/multirom/multirom.ini  # for Xenon HD, ROM_NAME would be Xenon\ HD
su -c sed -i 's/auto_boot_type.*/auto_boot_type\=2/g' /data/media/0/multirom/multirom.ini   # changing to `2` causes MultiROM to directly boot into the ROM mentioned in `current_rom`. The setting would later be reverted to 0 after successful boot
su -c reboot

Commands are optional here. You can use a file editor app, such as QuickEdit to edit the file.
Note: During reboot:

If auto_boot_type is found 1, the ROM selection UI would be shown after boot logo and it overrides auto_boot_rom which means after timeout the device would boot into whatsoever the current_rom has, automatically.

If auto_boot_type is found 3, device would boot straight into whatsoever the current_rom has, but, auto_boot_rom would also now be found same as the current_rom. auto_boot_type later reverts to 1 after successful boot.
I cannot comment on whether this is a bug or a desired behavior, but this is how it is.

Further note that I wouldn't be surprised if methods mentioned in this answer fails for a non-Android ROM.

I later realized that the major inconvenience in my solution, the touch input, can be stopped if I use Tasker's scenes in overlay blocking mode.
(Click image to enlarge)

I created several blank scenes and configured task to display them in such a way, that only a small fraction of screen can send touch input to app (fraction is allowed because I need to do input tap). The Manage ROMs window works well with DPAD key events so I used Task → Input → Dpad to reach my preferred ROMs entry and tap it.
To disable input from navigational keys, I used Xposed Additions Pro. Here are the relevant instructions. (Follow instructions there up to step 10.)
I also successfully tested AutoInput as an alternative for Xposed Additions. In a task, its relevant usage is:
Plugin → AutoInput → Modes:

Configuration:

Key Suppress: Enable
Keys: your navigation key

Timeout (Seconds): None

Make sure to enable its accessibility service in Settings → Accessibility.
This solution is not convenient as much as my other solution is, but it gets the job done.


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Difference between killing an app by clearing it from Recent Apps menu and “Force Stop”
What is the difference between these two methods when killing apps in Android?

Clearing an app from the Recent Apps menu by swiping it to the right or left.
Settings → App → Running → Force Stop.

Do they send the same signal (KILL or TERM) to the running process? Do they kill the services launched by the app?

See What actually happens when you swipe an app out of the recent apps list? and What does the "Force stop" button mean?

This question does not show any research effort.

Very usefull technical questions.im searching/posting this query in various forums but no reply.its very usefull

Although some people may think that clearing an app from Recent Apps menu will fully close it, they are unfortunately mistaken. There is a difference between clearing an app from Recent Apps menu and clicking Force Stop on it.
Clearing an app from Recent Apps menu may not fully close the app specifically the apps that use services such as Music Player, Whatsapp, Facebook, etc. When you clear Music Player for example, the music won't stop because the app uses a service running in the background, BUT if you force stop it from mobile settings, the music will stop hence the service is terminated.
So if you want to clear some memory to increase your RAM, you should force stop the apps that use services.
In conclusion, clearing an app from Recent Apps menu will only kill the activity lifecycle of the app but not the services that are run by that app.

Im searching for this .it's very usefull


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Can I cancel an Android update?
My Motorola Ultra is running 4.4.4 and I've been holding off on upgrading to the next one since I don't want to lose any possibility of getting root. However, this morning when the notification popped up, I accidentally selected "Don't remind me, just update at this time", the time being noon tomorrow. When it tries to start the update, is there anyway I can stop it?

I've already found this hopeful answer:

I just spoke to Google directly. The Nexus 5 under settings, apps has
something called Google Play services. Not store. If you uncheck the
notification box in Google Play services and restart the phone the
notification for the Android system updates will stop in the
notification bar. Worked like a charm!
From: How do I skip an Android system update and stop its notifications?

Moreover, if your devise had been rooted, you should be able to install Disable Services and find the SystemUpdateService under Google Services Framework. Disable it.
As you have device with Android Kitkat please read also that article: https://www.droidmen.com/how-to-stop-downloading-of-android-os-update-in-android-phone/
It should work.

I've edited my answer - new useful link added

My question is not about disabling notifications. It is about whether or not I can cancel a scheduled application of a firmware update.

sorry for my misunderstanding. You can cancel it for choosing ... later option. But look... stopping service like in the link doesn't stay forever, you can enabled it again at any disired time

Again, you misread what I wrote. I hit :later", but I had accidentally checked "don't remind me, just do it".

wait for installation time, I'm sure there would be option to re-think ;-)

I hope you are right.

It looks like there's no option to disable a in-progress update. Android upgrade is done by system ui. It will keep trying to download the incremental upgrade packages. After the download is finished, it will ask you to install the upgrade. And reboot upon your confirmation. You can decide not to install upgrade when it's prompting confirmation.


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Geometry Dash custom songs download location
I am currently using a Samsung Galaxy Xcover 3 (Model Number - SM-G388F) running KitKat 4.4.4. I would like to have some of these songs on my computer and phone, and this means that I need to find the download location.
Places that I have looked:

/data/data = Empty (no folders inside the /data folder)
/sdcard/Android/data/ = No folder for the correct Geometry Dash games
Nowhere visible on the root of the internal SD card

I am having trouble trying to find the application data location for any of my applications
Where do the custom songs download with custom levels in Geometry Dash get stored on the phone?
If it's relevant, the version of Geometry Dash is 2.011.

Related: Where Android apps store data? And sure, /data/data appears to be empty unless you check it with root powers :)

Can't root the phone as it is a loan from my family. But the best I can do is use Es file explorer with hidden files, this still doesn't show any folders inside the data/data/ area

To be more specific, one I click data, no folders show, meaning that I can't go data/data/ but rather just data/ with nothing else showing

Wrong, Matt. Those contents are not "hidden" in that way (which would mean names starting with a dot, like .hidden), but by OS/file-system permissions. Nothing ES can do about that unless your device is rooted. If /data/data would be really empty, that would mean your device was just factory-reset and not booted up after that :)

I figured as such, but it was worth a try To see if the music files were stored in a different directory

I would be able to adb to do this correct? Any instructions on using adb as I haven't used it much at all

Sure it was. If that were not an option, I'd written an answer instead of a comment :) I cannot verify that (not using the app), hence I only left a hint to the most likely cause. And no, ADB would also need root for that. Though you could try adb backup, and then investigate the resulting .ab file (see Is there a way to look inside and modify an adb backup created file?).

Thanks for the info about file systems, geuss it's time to use adb

Matt, you could use a root agent and unroot when the time comes

@Dan B I will justvuse ADB and then post van answer if I find the location of the songs, but the will have to wait till tomorrow for me

Alright. Let us know how it goes. Good luck!

well in the folder sdcard/android/data there is a geometry dash folder ( if you move geometry das hon sd card ) u can try that

@Shika as my other comments state, I believe it is in the data/data/ folder, but due to the fact that I don't have root, and do not want to root my Samsung phone, I have left this task for a later date. I now own the pc version and can now easily access any download song via thatbwaybif necessary

You'll need root access to find the folder.
Steps:

Root your phone
Install an application like ES File Explorer that has the root explorer function.
Go to /data/data/com.robtopx.geometryjump/files
Paste song, name of song must be song ID (Newgrounds)

Note: If you don't see the folders after /data/data, then either the file explorer doesn't support root explorer or your device is not rooted.

I'll mark this as an answer, Not sure if you read the above comments in my question, but we had come to the conclusion that it would be in the data/data/ folder (for which I would require root to access), I was relly hoping for when I asked this question that the songs would have been put into a custom location away from the data/data/ folder structure. Also as stated in the comments, I know have the steam version and as such this is no longer a problem for me.

I know you've already got an answer, but...
You could just search the song name in Newgrounds, which is where the songs are from, and then just click the giant yellow button that says "Download this song!"
::vv

Thanks for your contribution – but what is Newgrounds, and how does it help finding a file on the local device? OP didn't ask for internet sources to download from ("download location" in the context above means the place files were downloaded to, not from).


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Default rotation direction for landscape apps
My device is Samsung Galaxy S5 with Android lollipop.
Some games run on a landscape mode and the top-side becomes left-hand side and bottom becomes right-hand side.
Can I change this so that top goes right and bottom goes left?
I don't want to rotate my phone every single time I run these apps.

You can easily achieve this by automation. I prefer MacroDroid Being easy to learn and free
To understand how MacroDroid works and the settings required for your Android version, see  my answer
Your macro would look like this and you can tweak as you like
Trigger: Application Launched / Closed → Select your application
Action:  Force Screen Rotation →Force Landscape (or) Force Landscape 180 (Screen shot below shows possible options)
Constraints: None


text:
Stop Android from displaying "Install blocked" prompt
I am continually getting prompts for installing apps, such as Clean Master and or 9 apps on my Android phone. I turned off the option  "Install apps from unknown sources" in  security settings but then a message would popup saying "Install blocked" every time, as shown in the screenshot below.
So, how to stop these annoying prompts?
(Click image to enlarge)

Looks like you've caught some malware that tries to install all kind of stuff (follow the link for details). A factory-reset will certainly clear that, but that would mean losing all your data along the way. You might wish to check our most frequented malware questions for alternatives.

create download_1 folder where download folder exists . actually malware / ad it tries to create folder download_1 ..if exists it stops ..worked for me ..also scan using malware bytes ..or disable (Force Stop and then disable )PackageInstaller in system apps

You're better off with Izzy's advise and find and weed out the app trying to install that Clean Master app. Anyhow, there you go with an another solution.
When you attempt to sideload an apk using UI or any app that attempts to install an apk and isn't granted the permission android.permission.INSTALL_PACKAGES, Package Installer app comes into action and its activity PackageInstallerActivity is launched. The setting for unknown sources (install_non_market_apps) under Settings Storage's database is checked and based on that, you're either shown that prompt (dialog) or the permissions and the install button.
Even if you manage to find a hack that disables that prompt from being shown, Package Installer would still be launched and the UI would look awkward since only app's label and white space would be visible to you, which would do naught but create confusion.
For rooted Android
The solution I ended up with is to get rid of the activity PackageInstallerActivity. You can use Elixir 2 to disable that activity.
Launch it → Application → tap  → System applications → Package Installer → find and disable the said activity
You can also use adb in this case
adb shell su -c pm disable com.android.packageinstaller/.PackageInstallerActivity # Disables the activity
adb shell su -c pm enable com.android.packageinstaller/.PackageInstallerActivity # Use it to enable the activity

Now whenever you or an app attempt to sideload an apk which requires launching the Package Installer app, you may either get a toast like in the following image or an app registered to open/explore an apk would be launched or be suggested by system.
(Click image to enlarge)

If the toast becomes noisy, hide it using EnhancedToast1 or UnToaster2. Since they are Xposed modules, you would need Xposed Framework appropriate3 for your Android version.
Note that disabling that activity wouldn't affect the ability of Play Store to install an app, neither would it affect adb install because the underlying package manager is intact.
You can use automation here too. Example, whenever your preferred file manager is active on screen, enable that activity so that you can continue to sideload an apk, should you decide to, and keep it disabled for any other on-screen active app.
For non-rooted Android
You (KitKat or Lollipop users) can hide/block the whole Package Installer app. You definitely need adb for that.
adb shell pm block com.android.packageinstaller # for KitKat
adb shell pm hide com.android.packageinstaller  # for Lollipop

The biggest inconvenience here is that you won't be able to uninstall an app using Settings app because it uses Package Installer's activity named UninstallerActivity and UninstallAppProgress. Attempt to removal of an app using Settings app would cause the latter to crash.
Every time you intend to remove an app using Settings app or sideload an apk using UI, you must unhide/unblock Package Installer app.
To unblock/unhide, do
adb shell pm unblock com.android.packageinstaller # for KitKat
adb shell pm unhide com.android.packageinstaller  # for Lollipop

Note that hiding/blocking that app wouldn't affect the ability of Play Store to install an app, neither would it affect adb install because the underlying package manager is intact.

1: XDA: EnhancedToast
2: XDA: UnToaster
3. Xposed Framework: Android 4.x, Android 5.x and 6.x

I have a Chinese pad/phone that has built in system Trojans. The pad/phone was unusable with constant pop ups. I rooted it and it's was a bit better.
Malwarebytes was the only scanner that found 3 trojans.
All 3 were system trojans. I tried lots of ways to fix the problem nothing worked.
The main culprit was system the pad/phone has two system icons. One is the normal Cog. The other is a green droid.
By disabling the green droid system almost every problem gone.
Thanks to this post i installed Elixir 2. I disabled every thing in system that i don't use and it's now 99% better.


text:
Additional device "Nexus 7" in list of my devices
I went to list of my devices and I see always one non my device "Nexus 7".
It was strange, I immediately changed password and activated verifying with using mobile phone.
After that I login with my devices and Nexus 7 appeared again.
I made some investigations and I found that Nexus 7 appear only when I login on my tablet "Pipo M6". (Pipo M6 device also is in list of devices). Time (the last login) is a little different between Nexus 7 and Pipo M6.
It's a little strange, could you please explain me why I see this additional device.
It is possible that this situation related with SuperSU or other applications, which have root access ?

I think you may have malware on your Pipo tablet. Logout from tablet. Change password, delete from list Nexus and Pipo, finally per few days don't login on your tablet to make sure you're right ;-)

Start thinking on root your device and install CM http://forum.cyanogenmod.org/topic/82431-pipo-m6-pro/

@piotrek1543 I already did these actions. Only after I login on my pipo appears Nexus,

like i said you need to clean your android device. Check for popular Malware clean software for Android or root and install on it custom ROM like CyanogenMod

Ok, I will check malware.

Just to get the facts. Where is it that your seeing the "nexus 7"? Is it on the PC, Google account, WiFi network, or ???? There could be many reasons. We need further details, speculation isn't going to help fix your dilemma.


text:
Available memory of a 16GB microSD card?
Out of my newly bought Class 10 16GB microSD card I am getting only 14.71GB. Is this normal?

Yes, this is normal. Please read the "Customer confusion" part https://en.m.wikipedia.org/wiki/Gigabyte

Gigabytes are base 10, but Android uses Gibibytes (base 2)
See: http://www.wolframalpha.com/input/?i=16GB+to+GiB.
This is needed because binary data is written in base 2, but SI units are base 10.

Adding on to @GiantTree's answer, the binary-metric confusion is definitely one reason you encounter these kinds of differentially reported storage counts. Another thing is the formatting / file system overhead involved.
Normally, larger the SD card, larger will be the lost available storage due to the storage space required by the file system data structures like allocation tables, etc.
Android uses FAT32 or VFAT for SD cards by default, and, yes, this formatting does cause a significant loss in available storage.
Note also that newer Android devices or devices with modified kernels can support other file systems on the SD card such as ext4, NTFS or exFAT. All of these file systems have larger overheads compared to the FAT32/VFAT default, and ext4 and NTFS the highest among these.
As @Edgar posted, this can be thought of as the difference between the volume of a container measured internally and externally. The file system overheads account for the thickness, and the other part involves a different system of units used for measurement.
Put together, the decimal(metric)-binary confusion, file system overheads and also manufacturing issues cause this difference between advertised and reported storage capacity.
About manufacturing defects, I'm quoting from the accepted answer to this Unix&Linux SE question:

Typically a part of flash storage is faulty, and is marked so during manufacturing. There are also other bits that can go wrong (becoming unchangeable, unsettable, or unclearable), these parts must be marked faulty as well during the lifetime. This information is stored in a reserved space, on the same chips as your data. This is one of the several reasons a 4GB thumb drive is not showing 2^32 bytes capacity.

Also, all disks have 'bad sectors' which are not reported in the user available space.
Another thing that takes up space in a drive is the file structure inherent in the device itself.
A good way to understand this is to measure the exterior front wall of your house, then go from room to room, measuring the inside dimensions, omitting the interior walls and total up THOSE dimensions. Not the same, are they?

This answer seems a better fit for SuperUser than Android Enthusiasts. Please try to post an answer which is relevant directly to Android on Android Enthusiasts.


text:
adb>shell returns "error: closed" - how to "open" adb shell access through adb sideload
my device got broken but i am still able to connect usb in the stock recovery mode.
if i try to start a shell via adb while the device is in recovery mode, i fail. my terminal echos the line: "error: "Closed".
i think, because this device isnt rooted/cfw, the official firmware blocks the shell access in recovery. but there must be a way to connect.
what could i do to open a shell on this device?
just reinstalling another OS through sideload isnt a option, the only way to access data is through adb
-there is a option in the recovery: "update via adb/sideload". when i choose this mode i can execute via adb a sideload update. the device recognizes the file and executes it.
- if try this with the same setup but another rooted device, i success.

The behavior is status-by-design. Your stock recovery is not designed to grant shell access. Your only choice here is to somehow manage to flash a custom recovery.

To achieve something similar to what @Firelord suggested: TWRP can be booted on many devices without being installed. For that, find a matching image, then boot to the bootloader and run fastboot boot twrp.img. Btw: you can check with fastboot devices resp. adb devices whether a device is visible to the corresponding tool.


text:
Update WebView system component on KitKat
does anyone know a way to update the WebView system component on KitKat. I'm running 4.4.4, I think people get updates in Google Play in Android 5.0 and above but I would like to update it on KitKat and keep using this OS as it runs smoother for me, I'm sure there is a way to do this, can anyone help? The Webview on KitKat has some horrible bugs..
Thanks!

Did you go to playstore and install it?

I tried, but it says that it is not supported for my device, I think that only works for Android 5.0 and newer.

In Android 4.4 the webview component cannot be updated from the Play Store - it is fixed to version 30.0.0.0 (and 33.0.0.0 in 4.4.3). This was changed in Android 5.0:
https://developer.chrome.com/multidevice/webview/overview

In Android 5.0 (Lollipop), the WebView has moved to an APK so it can be updated seperately to the Android platform. To see what version of Chrome is currently used on a Lollipop device, simply go to Settings < Apps < Android System WebView and look at the version.


text:
After OTA update all my data are in shell folder
I have Acer Z530 with Lollipop 5.1, kernel 3.10.65+. I have the 16GB version, without external SD Card.
Today I have received an OTA update and after the restart all my data were gone as well as some 7GB of free space missing on the internal storage. When I connected using adb I have found all my data in folder /mnt/shell/emulated but the new data are being stored in /mnt/shell/emulated/0. So far I was able to find that the 0 is the default directory of the owner user. It seems that this update added the multiuser support, but failed to transfer the data.
How can I easily restore my data? Can I just mv everything to the 0 folder?
At this moment I'm pulling the folder to my PC, to have a backup, but I would rather do it correctly.

Using adb shell and mv command I was able to move all data to correct directory. After that, to be sure I did an restart and everything seems to be working correctly.


text:
Can the Network Operator know my whatsapp number on roaming?
If I am roaming and change the SIMcard, is the original Whatsapp data stored anywhere? Is there any way for -let's say the police- to track down all places I have traveled to?

In Android, actions such as accessing datas, running scripts, calling functions etc. are done by users which are simply applications. Every application got their own data folder that can't be reached by other apps. That includes your Whatsapp data too. Your GSM operator can't reach your Whatsapp data that is stored on your phone. However, since all data transaction is done through Whatsapp servers, should they get the required papers from a court, cops can ask or force Whatsapp to turn in the information the have about you, depending on the jurisdiction you live in.
Additionally, if you have a SIMCard in your phone that is in reach of any GSM towers, GSM company can detect of which tower you get your signal. They can even use satellites to pinpoint your location. But if you haven't at least murdered anyone, I don't believe any court would give that an OK. I don't think cops would try at all.
Also, SIM cards have very low internal storage area to store any actual information on them anyway.


text:
Google play services doesn't get installed
I just wanted to upload a video on YouTube but after updating the app to the latest version , it says that it needs Google Play Services to run. I tapped different places of the screen because it sometimes works with other apps, but this case is not the same. I tried hitting the back button and it just quit. I installed that Google app several times but it doesn't get installed. What should I do?

You can download the Google Play Services APK file from APK Mirror, just read the instructions on how to find the correct version for your device:  http://www.apkmirror.com/apk/google-inc/

You can download it from here,
you need to search for your android version.
http://www.apkmirror.com/apk/google-inc/google-play-services/
you need to download for your android version>4.1/4.4/5.1/6.0
or try to reinstall YouTube
I have the same problem.
I just download play services and problem was fixed.
EDIT:they support android 2.3+ im using old android phone now,and I can confirm that they support ,also confirm that it's  working for 4.0.


text:
My phone has a touch/pointing bug
I bought a new phone the other day and I noticed I can't deactivate an alarm from the Clock app, when I pressed the pink checkbox, it would not check. But this happens only for the top alarm, the other ones that are below the first one, work fine.
I started searching Google for a "touch" bug and the only thing that was a little helpful in my situation was finding the option to show the pointing circle on each touch. This allowed me to provide the next screenshot:

click screenshot for larger variant
So, when I try to press on something, say the checkbox on the first alarm, the device actually thinks I'm pointing in 2 directions at one, one above and one below.
Can somebody, please, provide me with some clearance on this issue? It's really annoying, given that the phone is brand new.

What is your phone? This isn't a problem with the clock app, you might have a faulty touchscreen. Take it to a service centre or ask for a replacement from wherever you bought it.


text:
Is it possible to stop certain apps from updating via Google Play?
A friend of mine updated a certain app and I don't like the choices the devs made. I'd rather stay on the current version. I know that I can set Google Play to not update apps automatically.
Thing is, I love being able to press UPDATE ALL to update all my apps with one press. Except for this app...
How can I make sure that this app does not appear in the Google Play updates section anymore?

No you can't remove it from update all list.

I am not sure if you don't want auto update or you if you want to remove it from the update all list. All apps will appear in the update all apps list. You can not remove them from that list.
To remove from auto update go to Google Play Store > Find the app you don't want to auto update > Select the 3 dots on the top right of the screen and deselect auto updates.

So, if I disable auto-update for an app individually by following that last line, does it mean that if there is any app update pushed to Play store, I won't be notified about it and if I check Update All list, that app won't be visible there. Am I correct?


text:
Android WebView upgrade/degrade issues
I'm using an Android application utilizing system WebView. After Android OTA upgrade up to 6.0.1, WebView's major version was 47. As far as I have had some issues with this version (specifically, webview sporadically hangs, and there is a similar issue logged - Android WebView stops loading pages), I decided to look for a fix.
According to WebView beta community, there was available more recent release of 47 major version (47.0.2526.99) than I have had (I do not remember my former minor version exactly, but it was older than 47.0.2526.99). Then I decided to try to update webview in Google Play. Indeed it shown me that an update is available for System WebView and I made the update.
As a result I received "newer" WebView with major version 46! This is just illogical to me. So I'd like to know: how is it possible to receive version updates which are downgrades in reality?
Unfortunately, in this "new" version I encountered another bug similar to what described in this issue ('javascript:' urls not working). So I'd like to make a rollback to my previous version. I noticed a menu in Google Play that says something about uninstalling the update for the webview. I clicked it, and as a result, I'm currently have webview with version 44!
Isn't this a mess? Shouldn't they prompt the user about exact version he will receive?
So the main question is: how one can ensure upgrade to the latest stable (or, at least, specified) version? If Google Play can provide outdated versions and even do not check if the device's already installed version is newer and overwrites it silently, then I just don't know what to think. Specifically I'd like to get the mentioned latest stable major version 47.
The 3-rd and the last question about the beta channel is voided now. It was absolutely unclear from the WebView Beta Community site, if stable WebView and beta WebView can live on the same device side by side, and if it is so, then how to embed one or another into an application. The answer is that installation of beta version means that the stable WebView will be replaced completely with the beta. This affects all applications using WebView, and this is definitely not how Chrome beta channel works (Chrome beta can work in parallel with stable versions and they do not interfere each other).

I'm sorry the question seemed too broad, but it was a single streamlined use-case, as you see: upgrade (the result is a mess), rollback (the result is even more mess). I'll edit just for clarity.

BTW, I don't remember I ever have had a notification about the question was closed. Not sure, if this is normal.

Did you leave the beta channel for WebView? If you left the beta channel, then Play Store will try to update (possibly downgrade) to the latest stable version. Otherwise, there might be a confusing version naming (alphanumeric) since Play Store and Android actually use version code (digit only) to decide the update. But to answer the main question: you can't. Play Store will only try to update to the latest version that is compatible (based on manifest and other Play Store filter) with your device. You can sideload the latest APK from alternative source manually though.

That said, Chrome Beta is not Chrome's beta channel, but a completely different app, so they can work in parallel. And also, OP is never notified when their question is closed/deleted.


text:
Where should I copy multimedia files on SD card?
I have a Huawei P8 Lite to which I added an SD card.
Using Windows Explorer, I'm not sure where to copy multimedia files so that the files will be found by eg. VLC.
The "SD Card" item contains the following directories:
.backup
Android
backup
DCIM
HuaweiBackup
LOST.DIR

Thank you.

Principially everywhere (except for LOST.DIR, Android and directories starting with a dot like .backup). Apart from that, you might wish to apply some "logic". Defaults are often:

Music: for your music files (have sub-directories below that if you like)
Video: for your video files
Pictures: for photos etc.
Books: for eBooks

Note that your Android device's camera stores its photos/videos below DCIM. The media-scanner will find your media files everywhere, unless you hide a directory and its contents by placing a .nomedia file into it. Several media players (and I assume VLC belongs into this category) also allow you browsing directories manually, independent from the device's media library.

Yeah, VLC scans the SD card and doesn't appear to depend upon mediaserver.

Glad to help, @Gulbahar – if it solved your issue, you can click the check-mark next to the answer to show that :)

You can copy your files to anywhere you want on your SD Card except the folders generated by the device like LOST.DIR, Android, and any other folder beginning with a dot like .backup. By default, any android device will search for multimedia files in all folders in the SD Card and recognize them using the system's MediaScanner. There is no specific folder, where you should copy to.
So for example, you can create these four folders in the root of your SD Card, and copy your files to them:

Music
Videos
Photos (sometimes people also like to put their photos in DCIM folder)
eBooks

Of course, you can name these folders anything you want and even create new ones as you like... If it happens that your device couldn't recognize any of your newly added files, just reboot your device and check them again, but that rarely happens.


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Mapping a key for calling the recent apps list
I have a new Nubia phone. After I installed Google Now, it overwrote the middle key long tap so that it shows the Now screen but I became unable to switch between recent apps. Moreover, the apps like Switchr cannot show recent apps since Android 5.0. How can I remap the button or call the recent apps screen any other way?

Not sure which one covers explicitly that, but be welcome to take a look at my list for apps to Edit Key Settings.

Do you not have the setting Buttons under Settings app? Is the device rooted?

@Firelord not rooted; cannot find settings for that. Should I root?

Yes, if you root you can easily change mapping of long-press of keys using Xposed Additions or Gravitybox [LP] app. Both of them requires Xposed Framework installed too. It means that you would need a custom recovery installed too.


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Using an old phone number with Whatsapp on a phone with no SIM card
I have the following situation, which though similar to other questions I believe not to be a duplicate.

I currently own a rather old iPhone with a SIM card installed and a new Android phone without. (There is a Verizon SIM card for the new phone, but I am leaving it unactivated it to avoid penalties from Verizon, which which I have no contract.)
I am in the US now on vacation, but new Android phone is intended to accompany me back where I live and not see service in the US in the foreseeable future.
I can't install my old SIM card on my new phone because it is the wrong size, and I am afraid of destroying it if I try to cut it down to nano-SIM size myself. (I guess I'll have to transfer my number to a new nano-SIM card from my provider when I arrive in my home country again.)

Now I would like to be able to use Whatsapp via Wi-Fi on the new phone with my old number and hence appear as my familiar old number to my old contacts. But Whatsapp demands, in order for me to use that number, that I have that SIM card on my new phone. If you send a SMS, rather than letting you respond from the old phone, it tells you it is waiting to autodetect the text on the new phone. When that fails, it offers to voice call the old number, but that number has no service in the US.
I am capable, on the other hand, of registering Whatsapp as a landline, through the voice call option, but this doesn't let me reach my old contacts through Whatsapp, and trying to change to my own number on this app activates the same sequence of countermeasures enumerated in the previous paragraph.
There are numerous solutions posted online, but most are of out of date and seem to be defeated by the current version of Whatsapp, specifically the facts that the SMS must be auto-detected or the voice call must be picked up. The most up-to-date solutions I've found suggest one log into Whatsapp on the web through the browser on the old phone to obtain a QR code scannable on the new phone, but the Whatsapp-on-the-web feature is unavailable to my old iPhone's OS, and upgrading to iOS 8.1 or higher would brick that phone.
But I'm still not willing to concede defeat. What can I do?

Contacts are not associated with Whatsapp accounts, only groups.

All right, I'm obviously misunderstanding any number of issues then. If I try to Whatsapp-text one of my contacts through this false landline account on my new phone, what will they see? Just the mystery number?

Yes. All data transactions (texts, images, sounds, videos etc.) between two clients are done through Whatsapp server. In the server, you are just an object with some parameters, one of them being your username, which is represented by the number that received the SMS code or call you used to activate the client.

I see. I guess I should modify my question. What I want is to appear to my contacts as myself in the guise they have known me.

If you want to do that, you should go to Whatsapp >> Settings >> Account >> Change Number. Your usename (which is your phone number) will migrate into the phone number you register using activation again.

That's the issue: I've tried to do this, but can't get through activation with the correct number: it will 1) send an SMS which my phone can't autodetect because it doesn't contain the relevant SIM card, then 2) send a voice card which my old phone can't answer because it's not in its native land.

If you can in any way be able to activate the code, it will work as your intention. No matter where you activate the code.

I'm not sure whether we're understanding one another, but I did figure out a way.

Here's what seems to have worked. The trick is that the system sends the same code via SMS and voice message. So in order, here's what happens.

The SMS is sent to the old number and received.
The Android phone tries and fails for five minutes to autodetect the SMS.
Whatsapp on the new phone then offers to voice call the old number, and asks you to enter the number you hear.
The voice call will never be received, but you can enter the number sent in the SMS anyway.

If you'd like to use Whatsapp on both devices, I've found, one falls down a different rabbit hole. By default, when Whatsapp associates your number with one device, it dissociates it from the other. I have not figured out how to defeat this yet.


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Prevent WhatsApp from automatically backing up messages
I noticed recently that WhatsApp automatically backups messages. I get a popup every now and then when I am using WhatsApp which says "Backing up messages". I don't want WhatsApp to backup my messages. I went into the WhatsApp settings and clicked 'Chats and calls -> Chat backup' and it says:
Local: 3:00am
Google Drive: Never

Google Drive settings shows that my settings are set to 'Never back up to Google Drive'.
With that said, how do I prevent it from backing up locally?

Quoting from WhatsApp FAQ How do I restore my chat history

If your device is plugged into your computer at night, low on storage space or is set to sleep with no background data; WhatsApp will not be able to backup your chat history.

I presume freeing up storage space is your reason for not wanting to back up. To do that

How do I delete WhatsApp back up? says

Your Chat History Backup files are saved in the /sdcard/WhatsApp/Databases/ folder.- You cannot open these folders outside of WhatsApp.- Make sure you have a file manager to be able to delete these files...

Launch your File Manager.
Tap on the WhatsApp folder, a list of all WhatsApp sub-folders will appear.
Tap and hold the Databases file.
Select Delete.

Wcleaner for WA. App description amongst other features claims (not tested by me )

Now you can delete or save WhatsApp backups (It is highly recommended not to delete latest backup)

There's no way to do that. WhatsApp updates its backup at 4 am(for me, can vary) everyday locally for easy recovery of chats.

'There is no way to do that'. You cannot prevent WhatsApp from taking backups, which is an answer to the question.

Oh okay. That was actually for another person who's comment seems to be deleted. Thanks.


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Disable Screenshot Security
Some apps don't allow screenshots so how can I still take a screenshot?
It is my phone and I should be able to do whatever I want with it so why is there even a feature to disallow screenshots?
Android 5.0.1

It doesn't matter what app it is (an online shopping app and an online banking app) it is the fact that apps have some kind of control of some features of my OS, what's next? Disallowing internet connection while having an app opened?

Go to setting and dont allow the app to control that permition

I can't edit the apps permissions nor is there such a permission for this type of control.

@Pali You'll have to play by the book unless you root your phone.

@SarpSTA well then I have found the final reason to root it ;)

Is it safe to say that all of the answers here require root?

Note: this answer is a bit outdated as of August 31, 2022. Will try to update it soon.
Why apps prevent screen capturing, and how to disable the restriction
Some apps present sensitive data (e.g. banking apps) or copyright-protected content (e.g. video streaming apps). App developers can opt to use the Android platform’s FLAG_SECURE setting to prevent the screen from being captured, recorded, or shown on “non-secure displays” such as the recent apps view. There are a couple of ways to disable this flag:

Smali Patcher module for Magisk. Magisk is officially supported on Android versions 4.2–12.0.
DisableFlagSecure module for Xposed. Xposed is officially supported on Android versions 5.0–8.1.

The Smali Patcher method requires you to connect your phone to a PC and run a Windows program to actually generate the module. Note that Magisk on Android 4.2 does not support MagiskHide.
The Xposed method has a big caveat: many banking apps use Google’s SafetyNet platform for checking device integrity, and prevent the application from being used on devices that have Xposed installed. This renders the module useless in SafetyNet-enabled apps, and there is currently no way to hide Xposed from SafetyNet.
Use these modules with caution, as they disable the flag system-wide.
Taking a screen capture of your phone on your PC
If you can’t or don’t want to disable FLAG_SECURE on your phone, you can also use scrcpy. It lets you mirror your phone’s display to your computer, and then you can just use a screenshot software of your choice on your computer to capture the phone’s screen. This requires you to turn on ADB debugging from your phone’s development settings, but beware that some apps restrict their functions when they detect that development settings are enabled. Scrcpy works on Android versions 5.0–12.0.

You can use Scrcpy or Vysor app and project your android screen to computer screen and then take screenshot on your PC.

I tried this and it did not work. Basically, since you are "casting" your screen through the Vysor app, screenshots will not work.

You have to take screenshots in your PC, not on mobile

On your PC you will get a black screen because Android determines that your app is using FLAG_SECURE. So that does not help. You clearly haven't tried this.

i have tried this with an app, which had screenshot disabled. It doesn't matter, whether the app is using FLAG_SECURE or not, the screen will get projected for sure

I can confirm that on Marshmallow this app does NOT work for secure apps at all.

TeamViewer would be another option to accomplish the same thing. Install the host app on your phone, then connect to it from your PC and take a screenshot of your PC screen.

I can confirm that I have used the TeamViewer Host app mentioned by @July.Tech to take a screenshot of an app that prevented direct screenshot on the phone. This was done on the Samsung Note 8 running Android 9.

@Hritik I can confirm that scrcpy works. I also had the problem that Vysor shows a black screen on my laptop but scrcpy always showed the screen and had no black screen issues with it.

There's also Smali Patcher program for Windows which creates custom Magisk module for your device and has option to disable FLAG_SECURE system-wide.

Apps which are set with LayoutParams.FLAG_SECURE flag do not allow screenshots (or videos recording) to be taken. It is of-course your phone but the app belongs to its owner (and he can rightfully wish to prevent users from capturing something sensitive in nature). You're barred from taking a screenshot only for those screens that have the above flag set. However you can still take a screenshot by projecting your phone on the PC screen and capturing it. That way, the device has no idea that screenshot is taken.

How does one project a "phone on the PC screen" and then capture it? Can you clarify if you are implying use of a separate or multiple different applications? Thanks.

"However you can still take a screenshot by projecting your phone on the PC screen and capturing it. That way, the device has no idea that screenshot is taken." That is missing a crucial aspect: Taking a screenshot should be a nearly instantaneous operation that should NOT require the use of a secondary device to aid the taking of a screenshot.

This answer is flase. For apps that use the FLAG_SECURE there is no way to project the app to another screen because the app won't allow it.

I have encountered this for LastPass. I don't see a reason why you would want to take a screenshot of one of your own passwords in-app. It actually holds your hand so you don't fuck up your own security.

"he can rightfully prevent wish to prevent users..." - I don't really care about his wishes. He doesn't have a legal right to prevent me (eg. It's not illegal to take a photo of my phone with another phone). Besides, lots of apps use FLAG_SECURE even when there is no sensitive data on the screen.

Just for those guys who came here by error in Chrome Incognito mode
Can't take screenshot due to error policy
There is a special flag Incognito screenshots that can be accessed via
chrome://flags

The default value is disabled but if you enable it, you are done. Screenshots are allowed.

In some banks you must log in first and disable security measures in regards to mobile applications. I did it with my bank.

I've found a workaround: from the app that is blocking screenshots press the Home button/gesture and then the Recents button/gesture so you can see the app you want to screenshot; you can then screenshot with the normal button shortcut or the on-screen "screenshot" button (and the resulting screenshot will not be blacked-out).
This worked for an over-zealous app which didn't want me screenshotting a specific screen but not for a well-made app (i.e. a browser in incognito mode), so it's almost certainly an exploit that might be patched rather than intended behaviour. Tested on android 9 and 12.

Following on from 'user's' answer, using a program such as Droid@screen droid at screen will allow you to project your phone screen to the PC, and then screenshot it via the PC Prnt Scrn button.
UPDATE:
Android screen mirror is a better and faster screen mirror
https://github.com/adakoda/android-screen-monitor


text:
wi-fi fails for a few days then starts working again
Several times over the past year the wi-fi failed then, after about 5 day, it started working again.
How to diagnose the problem?

resetting the phone's software restores the wi-fi connection
wi-fi icon says it is connected but it is unable to connect to the internet.
Connecting to the router IP address times out. All attempts to connect to the internet via wifi time out, as far as I can tell.
connecting to the wi-fi with other devices works fine
wi-fi routers are visible
Android version 4.2.2

Ideas?

for a start to diagnose the issue pull the logs and if more info is needed  the kernel logs (dmesg) too.


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How can I install Cyanogenmod on an up-to-date LG G2?
I acquired an LG G2 (LG-D802T 32 GB) that is running the most recent stock firmware. I'm trying to install Cyanogenmod on it. However, I cannot root it. The most recent firmware is patched against various rooting tools, including ioroot and Stump Root. I cannot find an alternative way to root this phone.
Are there other ways of rooting the LG G2? Is it necessary to root the phone in order to install Cyanogenmod, or are there other alternatives (e.g. "download mode")?
(I think I can first revert to an earlier firmware version that is unpatched, but cannot find an image for my model.)
EDIT
I've attempted rooting with the "New Root Method for LG Devices", adapted for Linux. This did not work. I also tried the more recent "Newest Root Method for LG devices", adapted for Linux, which also did not work.
I'm wondering what the dangers are for flashing the wrong firmware for my model. I know that there is an image for the Australian LG-D802T, but I don't know if this is for the 16 GB or the 32 GB. After downgrading to this image, this may hopefully re-expose the vulnerability required for rooting. If I accidentally flash the (incorrect) 16 GB version, but immediately install a custom ROM anyway, would that be a problem?

Have you checked xda-developers?

Have you checked the Cyanogenmod wiki?

@cricket_007 Thanks for the tip. I've found one guide, although I'm struggling a bit with Windows drivers. I'll try to adapt it for my normal OS (Linux).I'll report back shortly.

@xangua Yes, I linked the wiki in my question. They recommend ioroot, which doesn't work, as per my question.

I booted into Windows, and again attempted the most recent "Newest Root Method for LG devices". Similarly to when I tried it in Linux, this did not work, with the terminal freezing on the Send_Command.exe step. However, I cancelled this (with Ctrl+C) and tried this step again. This time it worked and I was able to root my phone. (Possibly, if I had tried it multiple in Linux it may have worked.)
I could then install Cyanogenmod as per the wiki, with a few caveats.

FreeGee did not support my device, so I used AutoRec instead.
The latest nightly cm-13.0-20160108-NIGHTLY-d802.zip refused to boot, so I used the latest release build cm-12.1-20151117-SNAPSHOT-YOG7DAO1KI-d802.zip instead, which is working fine.


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Merge Whisper c.db
Long story short I had to fully reformat my OnePlus One and when I restored Whisper from backup, the app no longer throws notifications to the status bar and the notification LED no longer lights on new activity.  Other apps work fine.
As a test, I uninstalled Whisper and re-installed it.  That time status bar notifications displayed.
Is there an easy way to merge an Android DB?  Some of the available SQL Lite tools don't list merging as a feature.

What do you mean by database?

/data/data/sh.whisper/databases/c.db

What do you mean by "merge" ?

I wish to take the stock DB and merge my DB into that one.  Hopefully keeping whatever throws status bar notifications that is somehow missing in my restored DB.

Ended up uninstalling Whisper then copying c.db from backup into the databases folder.  Now I get status bar notifications but the LED notifications still do not work.


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Can you install Android TV onto other devices?
I was wondering if it is possible to install Android TV on either the GameStick, Ouya, Mad Catz M.O.J.O, or any other device like that in order to breathe new life into these devices.

Or old smartphones, etc.


text:
How are internal components of Android tested before releasing?
How are the internal components of Android such as Zygote and Binder tested before being released?
I tried looking around for answers to this but most resources (blog posts and research papers) I could find dealt mostly with Android application testing and/or verification techniques for Android applications and not the system itself.
A (somewhat) related official information I found was Android Compatibility Test Suite(CTS). I suppose this is aimed at hardware vendors who customize AOSP code for their devices. CTS performs high level compatibility checks from user applications only but not all code of internal components is tested.
If there are no publicly known techniques currently being used in Android, are there any known techniques proposed for other operating systems which would be applicable for Android?
I am working on replacing some components of Android entirely and looking for efficient ways to test them (correctness, compatibility, security and more perhaps).
Edit: It is sufficient for me to know how internal components of Android such as Zygote and Binder are tested when changes are made to them. Since they are internal components, the testing could be very likely automated. Also, I am hoping to replacing these components with functionally equivalent code so these tests will help establish that no critical functionality has been affected.

Have you forgotten about the Developer Previews Google releases for testing to developers before every major Android version upgrade? What about those?

Also, this post about compiler reliability might give you an idea: http://programmers.stackexchange.com/questions/51966/how-come-compilers-are-so-reliable

And this quote by Linus Torvalds: "Given enough eyes, all bugs are shallow" (to paraphrase somewhat?)

Try the CTS itself first. Note that this is a user-focused site and ROM development related questions are considered off-topic here. Also, if you replace too much of the Android core, it might no longer be considered Android, and you would have to be on your own.

@TamoghnaChowdhury From what I read, CTS is primarily for testing devices that will run Android and not for testing Android itself extensively. I think developer previews are probably for testing compatibility of developer's apps with upcoming releases; they probably won't test internal Android components. Android internals would be quite complex to perform manual checks only.

Is there a better avenue of SE where I could ask about testing Android internals? It is sufficient for me to know how various internal components of Android system are tested before being released; will clarify this in question too.

This is the right place to ask that question, but the answer is the same for any piece of open source software, unit tests, large numbers of test cases, bug reports from technical users, etc. Also, the true core of Android is Linux, and that is bugchecked separately. As it stands, I suspect not even the most experienced users here are truly qualified to answer your question. You could ask it somewhere else, but I suspect it would just get redirected here. Try your luck.

I think this should have been posted in Stack Exchange. BTW, to answer your question, all device manufacturers who don't change the AOSP code (unlike Samsung's Touchwiz) do not test the software components since they are perfectly taken care by Google.

Your question should have been like "How are internal components of Android tested by Google before releasing?" To answer that question, AFAIK, the testing tools are not published by Google. They do that in virtual systems. I think the other companies who change AOSP have their own minimal tools or do the major testing manually.. Someone who has better experience like playing with CyanogenMod's deep source can help better.

@GokulNC Did you mean Stack Overflow when you said Stack Exchange is probably more appropriate?
Also, I didn't know that most manufacturers make mostly minimal changes which typically don't affect internal components greatly. Thanks for that info! I will wait to see if someone does answer this for CyanogenMod.

@dnivra Yeah I meant Stack Overflow..


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Delete system app using zip file
I have rooted my Huawei P8-Lite ALE-L21 with superuser.zip. After successful root I tried to change superuser app. So, I have installed KingoUser.apk and after that I have clicked on superSu app -> settings -> switch superuser app. It didn't work. So, I installed Link2SD app and converted KingoUser as a system app. Now, when I launching SuperSu or KingoUser, some warning message pops up and says that the su binary needs to be updated.
There is no way to flash my phone cause Huawei haven't released my build version as a stand-alone flash file.
How can I unroot my phone now ?

This topic will explane error and will solve the problem: http://android.stackexchange.com/questions/133194/remove-su-binary

Part 1 Unrooting Your Device
You can unroot your phone from SuperSu itselef
Go to SuperSu > Setting > Fullunroot.
Part 2: Replacing KingUser
You can download the ready to use script for replacing it with SuperSu Here

Download Zip file from site
Extract it in External Sdcard
Launch Terminal Emulator
Type su and give the superuser acess
Type sh /sdcard/mrw/root.sh
Script will automatically delete all Kinguser files amd will make SuperSu as system app
Update SuperSu binary

The default mount tool that comes with stock Android has its usage as Usage: mount [-r] [-w] [-o options] [-t type] device directory.

When you mount a partition from fresh, you do mount DEVICE_IDENTIFIER MOUNTPOINT. E.g., mount /dev/mmcblkp3 /system. When it comes to remount, you pass the option remount. If you want to remount at same location, you need not to pass device identifier, so it can be mount -o remount /system instead of mount -o remount /dev/mmcblkp3 /system. In order to mount in read-only or read-write mode, you pass ro or rw as argument. There are exceptions with mount tool in certain devices where you must mention device identifier during remount.

It's not working at all, and when I'm trying to use su with adb, this error goes up: error: only position independent executables (PIE) are supported.

Try su command from Terminal Emulator and see whether you are getting superuser access..If not than you can unroot as mentioned in answer..and can root again

i have tried that, same error.

look I've modified my own supersu.zip which have su binary in data/local directory, and it works fine with adb, now I have problem with removing old su binaries, please have a look here: http://android.stackexchange.com/questions/133194/remove-su-binary

Be careful! If you rashly attempt to install SuperSU after rooting with KingoRoot, your device would be bricked even if you uninstalled KingoRoot. KingoRoot will NOT completely remove itself when you uninstall it. The ONLY way to remove KingoRoot completely is to flash the stock ROM.
So, no, don't.

I don't think the question matches its title. However, this answer is for people who might arrive here in search for an answer to the question asked in the title...
how to delete system app using zip file.
First, see this answer where I explain how to create a ZIP file for flashing .apk files. Follow that explanation but use an updater-script like this:
mount("MTD", "system", "/dev/block/platform/mtk-msdc.0/by-name/system", "/system");
delete_recursive("/system/app/SomeApp");
unmount("/system");

Where SomeApp is the directory containing the .apk for the app that you want to delete (use an adb shell to acertain this path).
One could, however, just use adb shell to do it (but this doesn't answer the question asked):
$ adb shell
shell:/ $ su
root:/ # mount -o remount,rw /system
root:/ # rm -r /system/app/SomeApp
rppt:/ # reboot


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how to check that my phone (redmi note 4g ) was rooted before or not?
I want to know that how to check it out..
I have rooted my phone 3 times and unrooted also . my phone is in warranty so I  want to know it

SHA256 checksum of the system partition before rooting and after unrooting would differ. Enough to conclude that system partition has been tampered with. This is what block based OTA updates do to verify the integrity of the partition.

In redemi it doesnt seem to be possible if you have did the 'Full Unroot'

Additional Info. :
In some devices of motorola and sony bootloader need to be unlockeced from which company can find the device was rooted..and in some Samsung devices there is KNOX counter which changes on rooting..

2 steps to tell if your phone is rooted

First, download Terminal Emulator for Android app, if you don’t have one already on your phone.

Launch the app and you should get the well-known terminal interface with a text entry prompt.

Now, check the character right before your entry prompt.

If there’s a pound sign (#) then you’re rooted
Is there a dollar sign? If so, type in su and hit enter.
Should the dollar sign change into a pound sign (#), then you’re rooted!

NOTE: During that process, you might see a popup asking you to give
the terminal app superuser permissions, which you should grant.

Hope it help


text:
Nexus 10 - Android 5.0.1 OTA upgrade, “no command” and suggested steps failed
I did rooting with Kingo root, and also i did factory reset. but i still can't use OTG
When I press power+voldown, boot menu starts and immediately shows "Downloading... Do not turn of target!"
then i tried Hold Power + Volume Up + Volume Down, and then i can see recovery mode, but it still not working - no command ...
I still see "System update download" , still failed.
what can i try more?

you won't get the official updates on rooted Nexus devices

get custom rom like CyanogenMod or download ROM from Google site

What recovery? Stock, CWM,TWRP? It won't install like that. A factory reset won't remove root. You'll have to flash the stock images you can download from http://developer.google.com

Thanks for all your responses ^^ I will try custom rom or factory images and let you know again. Happy New Year!!

If you are planning on installing a custom rom you need to install a recovery to flash the the ROM. TWRP is good
To get Marshmallow on the Nexus 10 Omnirom is your best bet. You'll need to flash gapps and supersu for root too.
The nexus 10 received 5.1.1 security updates until April 2016 that you can get OTA on a stock device or install manually, but manual installs will wipe the content of the device each time.
The Unified Android Toolkit is good but the information is out there on the Nexus 10 Cyanogenmod page on how to flash a custom ROM from the command line.