retrieve text to Linux terminal for Android service run with adb

Issue

I would like an Android service (written in Kotlin) run in a Linux terminal to print out a message in the terminal it's running in. The main Kotlin class is in this file (I cloned that repo).

I'll want to modify that in various ways, but for now I just want to see if it's possible to print to the terminal. So I have tried adding statements like

print("message")
println("message")
Log.d(TAG, "message")
Log.i(TAG, "message")

etc. (see also this other SO question which suggested these, seemingly for a somewhat different purpose).

My problem:

While "message" does appear in the Android logs (viewed with adb logcat), and the message types match the type of logging I asked for (e.g. for Log.i it appears in the log as I <service-name>: message), I would nevertheless like to see it directly in the terminal where I have run the adb command that starts the service.

Is this possible?

Solution

I never did find out how to do this by calling an Android service via adb, so I resorted to a broadcast receiver instead.

My manifest file now registers the receiver:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.grobber.cliprecv">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".InfoScreenActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <receiver android:name=".MyBroadcastReceiver"  android:exported="true" android:enabled="true">
          <intent-filter>            
            <action android:name="get" />
            <action android:name="set" />
          </intent-filter>
        </receiver>
    </application>
</manifest>

(note that there's now no service at all for the app). In turn, the receiver class is defined in a Kotlin file as follows:

private const val TAG = "MyBroadcastReceiver"

class MyBroadcastReceiver :
    BroadcastReceiver() {    
                             override fun onReceive(context: Context, intent: Intent) {
                                 val clipboard = context.getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
                                 if (intent.getAction().equals("get")) {
                                     val res: String
                                     if (clipboard.hasPrimaryClip()) {
                                         val cliptext = clipboard.getPrimaryClip()?.getItemAt(0)?.coerceToText(context)?: ""
                                         res=cliptext.toString()
                                     } else {
                                         res = ""
                                     }          
                                     setResultData(res)
                                 } else if (intent.getAction().equals("set")) {
                                     val str: String? = intent.getStringExtra("text")
                                     clipboard.primaryClip = ClipData.newPlainText(TAG, str)    
                                 }                               
                             }
    }

Now, with the Android device connected to a computer and the app running in the foreground, running

 adb shell am broadcast -n com.grobber.cliprecv/.MyBroadcastReceiver -a get

will give me back the contents of the clipboard in my terminal as the data section of the output:

$ adb shell am broadcast -n com.grobber.cliprecv/.MyBroadcastReceiver -a get
---
Broadcasting: Intent { act=get flg=0x400000 cmp=com.grobber.cliprecv/.MyBroadcastReceiver }
Broadcast completed: result=0, data="<CLIPBOARD CONTENTS>"

---

Reference

The solution was adapted from this older app that similarly uses a broadcast receiver to get/set the clipboard.

Answered By - grobber