For CLI:

1. Download and install the Android SDK Package

2. Add a path to these two directories of the package install ([installedpath]/tools and [installedpath]/platform-tools for a full SDK installation).

3. Now, with the Android plugged in via the usb, run this to get the full list of installed apps:

   $ adb shell 'pm list packages'
   

   You now have a list the names of all your install apps.

4. Use the -f parameter to get the full pathname of a desired package by specifying a search string found in the previous list:

   $ adb shell 'pm list packages -f reader'
   

5. Now pull the full pathname of the package you want to get with:

   ## adb pull [filepathname] [destination path] ##
   $ adb pull /data/app/com.ebooks.ebookreader-2.apk ~/mybackupdir
   

For GUI you can use the app Airdroid.

For CLI:

1. Download and install the Android SDK Package

2. Add a path to these two directories of the package install ([installedpath]/tools and [installedpath]/platform-tools for a full SDK installation).

3. Now, with the Android plugged in via the usb, run this to get the full list of installed apps:

   $ adb shell 'pm list packages'
   

   You now have a list the names of all your install apps.

4. Use the -f parameter to get the full pathname of a desired package by specifying a search string found in the previous list:

   $ adb shell 'pm list packages -f reader'
   

5. Now pull the full pathname of the package you want to get with:

   ## adb pull [filepathname] [destination path] ##
   $ adb pull /data/app/com.ebooks.ebookreader-2.apk ~/mybackupdir
   

For GUI you can use the app Airdroid.

NOTE: 'pm' can be executed on the device, directly, with a Terminal Emulator, in order to locate the apk files. They can then be copied directly to the SD card, without computer intervention, nor the SDK. (note that 'cp' may not exist, so use e.g. 'cat file.apk > /mnt/extSDCard/file.apk')