Added: Add TERMUX_IS_DEBUG_BUILD, TERMUX_APK_RELEASE and TERMUX_APP_PID to termux shell environment

The `TERMUX_IS_DEBUG_BUILD` env variable will be set to `1` if termux APK is a debuggable APK and `0` otherwise. Note that the `dev_keystore.jks` shipped with termux app and plugin source code can also be used to create a release APK even though its mainly used for Github Debug Builds, in which case value will be `0`.

The `TERMUX_APK_RELEASE` will be set to `GITHUB_DEBUG_BUILD`, `F_DROID` or `GOOGLE_PLAY_STORE` depending on release type. It will be set to `UNKNOWN` if signed with a custom key.

The `TERMUX_APP_PID` will be set to the process of the main app process of the termux app package (`com.termux`), assuming its running when shell is started, like for `termux-float`. This variable is included since `pidof com.termux` does not return anything for release builds. It does work for debug builds and over adb/root. However, you still won't be able to get additional process info with `ps`, like that of threads, even with the pid and will need to use adb/root. However, `kill $TERMUX_APP_PID` will work from `termux-app` and `termux-float`.

These variables can be used by termux devs and users for custom logic in future depending on release type.

Author: agnostic-apollo

termux-shared/src/main/java/com/termux/shared/packages/PackageUtils.java

@@ -1,5 +1,6 @@
 package com.termux.shared.packages;
 
+import android.app.ActivityManager;
 import android.app.admin.DevicePolicyManager;
 import android.content.ComponentName;
 import android.content.Context;
@@ -248,4 +249,30 @@ public static String getProfileOwnerPackageNameForUser(@NonNull Context context)
         return null;
     }
 
+    /**
+     * Get the process id of the main app process of a package. This will work for sharedUserId. Note
+     * that some apps have multiple processes for the app like with `android:process=":background"`
+     * attribute in AndroidManifest.xml.
+     *
+     * @param context The {@link Context} for operations.
+     * @param packageName The package name of the process.
+     * @return Returns the process if found and running, otherwise {@code null}.
+     */
+    @Nullable
+    public static String getPackagePID(final Context context, String packageName) {
+        ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
+        if (activityManager != null) {
+            List<ActivityManager.RunningAppProcessInfo> processInfos = activityManager.getRunningAppProcesses();
+            if (processInfos != null) {
+                ActivityManager.RunningAppProcessInfo processInfo;
+                for (int i = 0; i < processInfos.size(); i++) {
+                    processInfo = processInfos.get(i);
+                    if (processInfo.processName.equals(packageName))
+                        return String.valueOf(processInfo.pid);
+                }
+            }
+        }
+        return null;
+    }
+
 }

termux-shared/src/main/java/com/termux/shared/shell/TermuxShellUtils.java

@@ -20,6 +20,11 @@
 
 public class TermuxShellUtils {
 
+    public static String TERMUX_VERSION_NAME;
+    public static String TERMUX_IS_DEBUG_BUILD;
+    public static String TERMUX_APK_RELEASE;
+    public static String TERMUX_APP_PID;
+
     public static String getDefaultWorkingDirectoryPath() {
         return TermuxConstants.TERMUX_HOME_DIR_PATH;
     }
@@ -36,13 +41,16 @@ public static String[] buildEnvironment(Context currentPackageContext, boolean i
 
         List<String> environment = new ArrayList<>();
 
-        // This function may be called by a different package like a plugin, so we get version for Termux package via its context
-        Context termuxPackageContext = TermuxUtils.getTermuxPackageContext(currentPackageContext);
-        if (termuxPackageContext != null) {
-            String termuxVersionName = PackageUtils.getVersionNameForPackage(termuxPackageContext);
-            if (termuxVersionName != null)
-                environment.add("TERMUX_VERSION=" + termuxVersionName);
-        }
+        loadTermuxEnvVariables(currentPackageContext);
+
+        if (TERMUX_VERSION_NAME != null)
+            environment.add("TERMUX_VERSION=" + TERMUX_VERSION_NAME);
+        if (TERMUX_IS_DEBUG_BUILD != null)
+            environment.add("TERMUX_IS_DEBUG_BUILD=" + TERMUX_IS_DEBUG_BUILD);
+        if (TERMUX_APK_RELEASE != null)
+            environment.add("TERMUX_APK_RELEASE=" + TERMUX_APK_RELEASE);
+        if (TERMUX_APP_PID != null)
+            environment.add("TERMUX_APP_PID=" + TERMUX_APP_PID);
 
         environment.add("TERM=xterm-256color");
         environment.add("COLORTERM=truecolor");
@@ -147,4 +155,21 @@ public static void clearTermuxTMPDIR(boolean onlyIfExists) {
         }
     }
 
+    public static void loadTermuxEnvVariables(Context currentPackageContext) {
+        TERMUX_VERSION_NAME = TERMUX_IS_DEBUG_BUILD = TERMUX_APK_RELEASE = TERMUX_APP_PID = null;
+
+        // This function may be called by a different package like a plugin, so we get version for Termux package via its context
+        Context termuxPackageContext = TermuxUtils.getTermuxPackageContext(currentPackageContext);
+        if (termuxPackageContext != null) {
+            TERMUX_VERSION_NAME = PackageUtils.getVersionNameForPackage(termuxPackageContext);
+            TERMUX_IS_DEBUG_BUILD = PackageUtils.isAppForPackageADebugBuild(termuxPackageContext) ? "1" : "0";
+
+            String signingCertificateSHA256Digest = PackageUtils.getSigningCertificateSHA256DigestForPackage(termuxPackageContext);
+            if (signingCertificateSHA256Digest != null)
+                TERMUX_APK_RELEASE = TermuxUtils.getAPKRelease(signingCertificateSHA256Digest).replaceAll("[^a-zA-Z]", "_").toUpperCase();
+
+            TERMUX_APP_PID = TermuxUtils.getTermuxAppPID(currentPackageContext);
+        }
+    }
+
 }

termux-shared/src/main/java/com/termux/shared/termux/TermuxUtils.java

@@ -533,4 +533,16 @@ public static String getAPKRelease(String signingCertificateSHA256Digest) {
         }
     }
 
+
+    /**
+     * Get a process id of the main app process of the {@link TermuxConstants#TERMUX_PACKAGE_NAME}
+     * package.
+     *
+     * @param context The context for operations.
+     * @return Returns the process if found and running, otherwise {@code null}.
+     */
+    public static String getTermuxAppPID(final Context context) {
+        return PackageUtils.getPackagePID(context, TermuxConstants.TERMUX_PACKAGE_NAME);
+    }
+
 }