Develop Reference

Adb: ignore offline devices?

When multiple android devices are attached, but only one of them is in debug mode, adb install|shell|... will fail with
error: more than one device/emulator
Obviously, that issue can be fixed by specifying the serial of the online device, either via ANDROID_SERIAL or a -s parameter. For fixed build scripts under version control, it would imho be better to just use the only possible device if there is only one.
Why does adb take offline devices into account? Is there a way to change that behavior?
Note: I'm searching for pure adb answers; I'm aware that I can script a call to adb devices extracting the serial of the only device, if any. But it just feels wrong for such a simple issue...

Adb backup does not work

I need help from you guys, because I don't know what I did wrong with adb backup.
I want to backup my Samsung Galaxy S3 LTE (GT-I9305) without root. I googled it and found Full Android Backup with SDK Manager. I installed all i need for this like Java Development Kit 8 version 66 (JDK 8u66 x64) and Android Studio which contains SDK Manager. Then they sad i should download the Google USB Driver. I downloaded it but nothing happened. I thought it should work now and then I went to C:\Users\MYNAME\AppData\Local\Android\sdk\platform-tools and left-clicked adb whilst holding Shift. Then I clicked "Open command window here". After this I typed in "adb devices" and it said:
List of devices attached
3204cfaaf8611199 device
Then I typed in:
adb backup -apk -shared -all -f C:\Users\NAME\backup.ab
It said
Now unlock your device and confirm the backup operation.
I did this and my Smartphone opened "Full Backup" and then I was able to set a password for the backup. I don`t need a password and I just clicked "Back up my data" Then it went back to my homescreen and said "Starting backup..." as a toast message and immediately after this it said "Backup finished" and created a backup file with 40 bytes. I don't know what I should do now.

Rather than trying to find an old version of adb, it's easier to add quotes to the arguments to adb backup :
adb backup "-apk -shared -all -f C:\Users\NAME\backup.ab"

The line, which correctly invokes adb, needs to look like this at my side:
adb backup "-apk -obb -shared -all -system" -f phone-20180522-120000.adb
This line is for Linux, but should do for Windows and OS-X as well. For Linux (and probably OS-X), you can use a script like following, which automatically assigns a timestamp to the file:
adb backup "-apk -obb -shared -all -system" -f "${PHONE:-phone}-`date +%Y%m%d-%H%M%S`.adb`"
Important After doing a backup, verify your data! At my side, sometimes some corruption of the file shows up (and I doubt it is my computer, as I only observe such errors with adb).
Here is a check instruction I use:
set -o pipefail
for a in *.adb;
do
echo "$a";
dd if="$a" bs=24 skip=1 | zlib-flate -uncompress | tar tf - >/dev/null;
echo "ret=$?";
done
It should show ret=0, but it doen't.
If you see inflate: data: invalid code lengths set your archive is corrupted and - very likely - unusable for restore!
If you see tar: Unexpected EOF in archive your backup probably is usable (all backups end this way, I do not know why).
Even if you see just ret=0 there might be undiscovered errors which still prevent a restore.
There is definitively missing an adb verify command, to verify correctness of a backup!
FYI
I post this update, as all other answers were helpful, but not exact to the last detail. (When used with full quotes, a backup was done, but called backup.ab)
Here is my environment:
OS: Ubuntu 16.04
Phone: Android 7.0
ADB: 1.0.32
The full procedure was (just in case somebody stumbles upon this not knowing what is needed):
Zeroth: Install adb (on Ubuntu: sudo apt-get install android-tools-adb)
First: Enable USB debugging mode on the phone.
Second: Attach phone to USB of the computer with an USB data cable (a charge only cable is not enough)
Note that the Ubuntu Phone Manager might show up and ask you for the phone's PIN. You do not need that, close this if it happens.
Third: run adb devices - you should see something like XXXXXXXXXXXX unauthorized
After some time on your phone a message shows up which asks for USB debugging permission
Allow this once. For security reasons, you should not automatically trust the computer, as the fingerprint can be easily faked.
Note that if something is obstructing a single pixel of this confirmation window (like some accessibility feature button) you cannot tap on the OK. First move the obstructing window.
Forth: Now again run adb devices - you should see something like XXXXXXXXXXXX device
If more than one line shows up, you attached more than one phone to the computer. The easy way is to unplug all those you do not want to backup. (The complex way is to set the environment variable ANDROID_SERIAL=XXXXXXXXXXXX.)
Now run adb backup as shown above. Change the file to your needs.
This brings up a window which asks for backup permission.
Do not close the backup window while the backup is taken. When I tried this, the backup stopped and the resulting archive was broken.
You can give a password to encrypt your backup. I do not have any information on how secure the password is. But it is very likely, that you cannot restore the backup taken in case you ever forget this password.
I have no idea on how to restore such a backup to other phones. I even never tried the restore, so I cannot help here, too.
Notes:
adb help shows all possible options to adb backup
Close all open applications on your phone before the backup. I do not know if this is needed, but it certainly cannot hurt.
Leave the phone alone while the backup runs. I do not know if this is needed, but it certainly cannot hurt.
Do not be impatient. Leave the backup plenty of time. At my side I see a progress of about 100 MB/Minute (YMMV). So the backup takes about half an hour for my phone (2.5 GB).
Apparently adb backup does not completely backup everything!
I had a look into the backup (cd X && dd if=../XXXX.adb bs=24 skip=1 | zlib-flate -uncompress | tar xf -) and did not find all installed applications.
What I was able to find was (note that this list is incomplete):
Internal emulated SD-Card: shared/0
External SD-Card: shared/1
Apps: apps/ - many apps (like Google Authenticator) were missing
Calendar: apps/com.android.providers.calendar/db/calendar.db (probably)
What I was not able to find (note that this list is incomplete):
Alarms. (I was probably not able to detect the right app)
Full external SD-card (there is more on this card than what is shown below share/1. For example the apps, which are moved-to-SD.)
Conclusions:
Sometimes adb backup might create corrupt backups, which can go unnoticed. So either check your backup or do frequent backups and pretend to be lucky enough such that not all backups go corrupt.
With adb backup you get a backup of most of your precious data, like camera images and so on. It might be a bit difficult to unpack it, though.
adb backup is not enough to do a complete backup of your phone.
adb backup is not enough to backup your SD-card such, that if it breaks, you are able to replace it by a new one with the contents restored. This is very sad!
PS: The typo "Forth" is not an accidental one.
PPS: zlib-flate can be found in package qpdf on Ubuntu 18.04

This just worked using Ubuntu 15.10 ("wily") to backup a Galaxy SM-G900V running Android version 6.0.1.
Installed using:
sudo apt-get install android-tools-adb
Then I ran the following from the command line (without 'sudo'):
adb backup -apk -shared -all -f backup.adb
Result:
user#hostname:~/droid$ ls -lah
total 1.2GB
drwxrwxr-x 2 user user 4.0BK Mar 6 18:43 .
drwxr-xr-x 52 user user 4.0KB Mar 6 17:40 ..
-rw-r----- 1 user user 1.2GB Mar 6 18:29 backup.ab
Thank you "NG". I was beginning to think my phone was borked.
Forgot to add: Running adb version: Android Debug Bridge version 1.0.31

Seem not all apps can be backed up. Android apparently allow apps to disable backup :(
https://developer.android.com/guide/topics/manifest/application-element.html (search for allowbackup)

The problem is the adb version of your PC. Using adb version 1.0.31 the backup/restore will be sucessfull.
More info on: https://android.stackexchange.com/questions/83080/adb-backup-creates-0-byte-file-prompts-for-current-backup-password-even-though
and How to downgrade my SDK Version?
If your device has an adb version prior to 1.0.31, then you must use an adb version of 1.0.31 on PC. Versions of adb 1.0.32+ broken the backwards compatibility. Source: Issue 208337

Just incase anyone is still having trouble - In windows, I found putting the quotes around only the directory, for example "C:\Users\NAME\backup.ab" worked.

I found this solution :
adb backup -apk -shared -all -f "<path-where-the-backup-will-be-created>.ab"
And to restore :
adb restore "<path-where-the-backup-is>.ab"

Removing an sqlite db in Android

I'm debugging my android app in Android Studio using a real android device and. I see that the Sqlite db path is
/data/data/com.my_app/databases/data1.db
I want to remove it. By that path doesn't exist when try to find it by a file manager. And, of course, this isn't working:
adb -e shell rm /data/data/com.my_app/databases/data1.db
adb server is out of date. killing...
* daemon started successfully *
error: device not found
So how can I remove it and why isn't it visible in my smartphone?

why isn't it visible in my smartphone?
Because it is on internal storage, which you do not have access to, except on emulators and rooted devices.
And, of course, this isn't working:
That is some separate problem with adb running on your machine.
So how can I remove it
If you want to completely clear your app's data (databases, SharedPreferences, and other files) on internal storage, use the Settings (e.g., Settings > Apps > (your app) > Clear Data on Android 4.x/5.x).
If you specifically want to get rid of this file on an emulator, the command you tried should be fine. I suggest restarting the emulator.
If you specifically want to get rid of this file on production hardware, you will need to use run-as:
adb shell run-as com.my_app rm /data/data/com.my_app/databases/data1.db

You can't reach that directory if your device isn't root . For change or modify system files you must have root access .

how could I transfer file from terminal to screen /dev/tty.*(android machine)?

I'm developing android set-top box app.
So, I have android box and its adb is REALLY SLOW.
When I have to install .apk file to debug my project, I use adb connect [ip address] via wifi and then build & run with Android Studio because the set-top box doesn't have USB port.
But it has serial port so I can connect its shell by screen /dev/tty.usb-serialblablabla 115200. when I use that command, I can see exactly same screen as one of adb shell.
Its adb shell(via wifi) shows very very slow performance.
For example, if I want to run pm list packages, I should type 'pm list packages' and wait for 2min.and then type enter key.(...sigh)
Whereas,Using screen /dev/tty.* methods respond promptly.
I don't know where this difference is come from.
but it is not matter of wifi. I checked its speed. it is quite normal.
In this circumstance, I click Run button in Android Studio after adb connect.
gradle build takes about 10sec.
upload .apk(10.2mb) takes about 10min (sigh).
Because screen ... way is much faster then adb connect way, I want push my .apk into device via 'screen'. how can I do? OR is there anything I can do to reduce time for putting .apk in android device?

You really should find out why adb transfers take so long. But if you insist on using serial console for uploads instead - you could just use any terminal application with XMODEM support on PC side to send the file and busybox rx -b <filename.apk> command on android side to save it. Then pm install <filename.apk> to install it.

ADB Install needs Root ? vs Eclipse Install?

I try to understand how this works:
When I create an android app and run it from Eclipse, Eclipse takes care of generating the apk file and uses adb to install it on the phone correct?
When I have an .apk file that I try to push on the phone and use ADB directly in a command line by calling adb install myApp.apk I can't because my phone isn't rooted?
How does Eclipse manages to install apps then?
Is there a way to install from an .apk file on a device without having it rooted ? Obviously Eclipse is able to.
Thanks for any information that may help clarifying this.
David

So the really short answer to your question; You don't need to be rooted to use ADB, all android phones can use ADB without being rooted.
Also, the only reason you would need root is to mess with things on the system level, when installing a regular app you are just installing it like a regular application (to the data partition). Eclipse installs the app using ADB actually, so pushing an app using ADB is the same as installing it through eclipse.
You don't need to be rooted to use ADB, all android phones can use ADB without being rooted. You must be rooted to push applications to /system/apps/ to make them system applications. Also if you download a file explorer like ES File Explorer to your phone, you can transfer an apk file to your phones storage and using a file explorer (I really do recommend ES File Explorer) you can install that app.
Also just a tip, to use ADB command line you must enable ADB on your phone in developer settings.
Go to the settings menu, and scroll down to "About phone." Tap it.
Scroll down to the bottom again, where you see "Build number."
Tap it seven (7) times. After the third tap, you'll see a dialog that says you're four taps away from being a developer. Keep on tapping and the developer settings will show up in the settings app. There you can turn on ADB.
Hope this helps.
Further Reading: http://developer.android.com/tools/help/adb.html
http://www.androidcentral.com/how-enable-developer-settings-android-42