Get result code of adb shell command

Question

How should I get $? of adb shell <command>?

I would like to check the result of adb shell mkdir /xxx.

I executed mkdir command by adb shell and failed but the result of $? is 0.

$ adb shell mkdir /xxx mkdir failed for /xxx, Read-only file system $ adb shell echo $? 0 $ adb shell "mkdir /xxx; echo $?" mkdir failed for /xxx, Read-only file system 0 

I would like to get the result code of adb shell <command>but not in the interactive mode like below:

$ adb shell shell@android:/ $ mkdir /xxx mkdir failed for /xxx, Read-only file system 255|shell@android:/ $ echo $? 255 

Answer 1

You should do:

$ adb shell 'mkdir /xxx; echo $?' mkdir failed for /xxx, Read-only file system 255 

Notice the single quotes, otherwise $? is evaluated before reaching adb.

Answer 2

If you are using an older emulator, then adb shell does not return the exit value. Then you have to use adb shell 'false; echo $?' like in https://stackoverflow.com/a/17480194/306864

In newer emulators, it works properly, then you can do adb shell false || echo failed. Here's how I tested:

$ adb -e android-22 shell false; echo $? 0 $ adb -e android-22 shell 'false; echo $?' 1 $ adb -e android-29 shell false; echo $? 1 $ adb -e android-29 shell 'false; echo $?' 1